travis: Add linter to detect multiple blank lines between paragraphs (#66)

* travis: Add linter to detect multiple blank lines between paragraphs

* Use one blank line between paragraphs

* Remove trailing spaces

.travis.yml

@@ -15,4 +15,5 @@ script:
   - git grep $'\t' -- "*.asciidoc" "*.md" && echo "^ Use of tabs detected. Please use space for indentation." && exit 1 || true
   - git grep "[^ ]  [^ ]" -- "*.asciidoc" "*.md" && echo "^ Satoshi style double spacing detected. Sorry Satoshi, please use single spacing." && exit 1 || true
   - git grep -iE '(^| )(\w+) \2(\.|,|:|;| |$)' -- "*.asciidoc" "*.md" && echo "^ Detected lexical illusion in the form of a duplicated word. Please correct." && exit 1 || true
+  - git grep "" -- "*.asciidoc" "*.md" | uniq -c | grep -1 "^      [2-9] " | cut -b9- | sed 's/:$/:[more-than-one-blank-line-here-please-remove]/' | grep ":" && echo "^ Multiple blank lines detected. Please use only one blank line between paragraphs." && exit 1 || true
   - codespell --ignore-words-list=que $(git ls-files -- "*.asciidoc" "*.md")

CONTRIBUTING.md

@@ -72,7 +72,6 @@ As we saw in <<intro_to_ln>>, the intro paragraph is superb!
 
 ```
 
-
 ## Line endings
 
 All submission should use Unix-like line endings: LF (not CR, not CR/LF). All the postprocessing is done on Unix-like systems. Incorrect line endings, or changes to line endings cause confusion for the diff tools and make the whole file look like it has changed.

ch01.asciidoc

@@ -97,7 +97,6 @@ Also Hearn referred to a section on the contracts article talking about the case
 Links:
 * https://en.bitcoin.it/w/index.php?title=Contract&oldid=36712#Example_7:_Rapidly-adjusted_.28micro.29payments_to_a_pre-determined_party
 
-
 * Multiple white papers
 ** Joseph Poon, Thaddeus Dryja - The Bitcoin Lightning Network:
 Scalable Off-Chain Instant Payments https://lightning.network/lightning-network-paper.pdf
@@ -160,10 +159,8 @@ However with the LN, she knows that her regular clients, such as Joerg can pay f
 Additionally, by using the LN, Silke has all funds deposited instantly to her wallet and with usually smaller fees on her side as well.
 Ultimately this allows her to provide a better service or to offer better pricing for her products.
 
-
 === Getting Started
 
-
 ==== Choosing a Lightning Network Wallet
 
 * full nodes (c-lightning, eclair, lnd) + remote controls
@@ -183,7 +180,7 @@ Ultimately this allows her to provide a better service or to offer better pricin
 * Trade fiat for Bitcoin (as in Mastering Bitcoin)
 
 [[using_own_bitcoin]]
-==== Process for people who already own Bitcoin ==== 
+==== Process for people who already own Bitcoin ====
 
 * send bitcoin to lightning wallet (1 onchain transaction - soon nodes / wallets may support funding a channel directly without sending bitcoins to the lightning network wallet first)
 * find a node to open a channel with (Node explorer / Autopilots / ...)
@@ -191,12 +188,11 @@ Ultimately this allows her to provide a better service or to offer better pricin
 * open a channel
 * wait confirmations for the channel to become operational
 
-
 [[sending_receiving]]
 ==== Sending and Receiving Bitcoin on the Lightning Network
 * have the person who helps onbording open a payment channel (As complex as a bitcoin transaction)
 * showcase how the funds now can be send back and forth
 ** create invoice
 ** decode invoice (do always before paying!)
-** pay an invoice 
+** pay an invoice
 * showcase how an arbitrary invoice can be paid e.g. https://voting.ln.rene-pickhardt.de

ch02.asciidoc

@@ -75,7 +75,7 @@ an alternative structure for the subsections of the invoice section (while cover
 * construct an onion using
 ** SPHINX
 ** payment hash
-** path 
+** path
 
 ==== Payment Forwarding Algorithm
 
@@ -93,4 +93,4 @@ an alternative structure for the subsections of the invoice section (while cover
 * waiting for confirmations vs instant settlement (if everything works smoothly)
 * arbitrary amounts vs capacity restrictions
 * variying fees depending on the traffic vs announced fees (might become dynamic too?)
-* blockchain to save all transactions vs blockchain as a court system 
+* blockchain to save all transactions vs blockchain as a court system

contrib/example.asciidoc

@@ -4,7 +4,6 @@ License: CC-BY
 Added By: @aantonop
 ////
 
-
 == Basis of Lightning Technology (BOLT)
 
 The Basis of Lightning Technology (BOLT) documents describe a layer-2 protocol for off-chain bitcoin transfer by mutual cooperation, relying on on-chain transactions for enforcement if necessary.

preface.asciidoc

@@ -24,7 +24,6 @@ _Italic_:: Indicates new terms, URLs, email addresses, filenames, and file exten
 
 _++Constant width italic++_:: Shows text that should be replaced with user-supplied values or values determined by context.
 
-
 [TIP]
 ====
 This icon signifies a tip or suggestion.
@@ -121,7 +120,6 @@ Follow us on Twitter: link:$$https://twitter.com/oreillymedia$$[]
 
 Watch us on YouTube: link:$$https://www.youtube.com/oreillymedia$$[]
 
-
 ==== Contacting Andreas
 
 You can contact Andreas M. Antonopoulos on his personal site:
@@ -142,7 +140,6 @@ link:$$https://linkedin.com/company/aantonop$$[]
 Andreas would also like to thank all of the patrons who support his work through monthly donations. You can support Andreas on Patreon at
 link:$$https://patreon.com/aantonop$$[].
 
-
 ==== Contacting Rene
 
 You can contact Rene Pickhardt on his personal site:
@@ -162,7 +159,6 @@ link:$$https://patreon.com/renepickhardt$$[].
 
 Or you can support his work directly with bitcoin (also via the Lightning Network) at link:$$https://tallyco.in/s/lnbook$$[] for which Rene is equally thankful as for his patreons.
 
-
 [[acknowledgments_sec]]
 === Acknowledgments by Andreas
 
@@ -178,7 +174,6 @@ I am also grateful to the Bitcoin and Lightning Network community who welcomed m
 In particular I am grateful to all the open source Bitcoin and Lightning Network protocol developers and people who fund them to make that technology possible.
 Last but not least I am thankful to my loved ones.
 
-
 [[github_contrib]]
 === Contributions
 

topics.asciidoc

@@ -103,7 +103,6 @@ While also important for end users to be aware of some of the topics here it is
 * uptime
 * watchtowers
 
-
 === BOLT 1.0
 A summary of how the Lightning Network protocol works.
 
@@ -137,7 +136,6 @@ A summary of how the Lightning Network protocol works.
 * Transaction Malleability
 * Transport Layer
 
-
 === BOLT 1.1 / 2.0
 Future trends and developments on the Lightning Network.