This commit standardizes the various todos around the code a bit in a manner recognized by LDoc.
Besides drawing more attention by being displayed in the developer docs, they're also extractable with LDoc on the command line:
```sh
ldoc --tags todo,fixme *.lua
```
However, whether that particular usage offers any advantage over other search tools is questionable at best.
* and some random beautification
The "My Clipping" file that storing highlights and notes for Kindle
native readers could also be parsed and exported. The parser is
implemented in `evernote.koplugin/clip.lua`.
Parsed highlights and notes in one book will be packed and rendered
into html node with a slt2 template `note.tpl` that complies with
evernote markup language(ENML).
Finally the evernote client will create or update note entries and
push them to Evernote cloud.
