README: nccell not cell, update Sixel question

README.md

@@ -81,7 +81,7 @@ Why use this non-standard library?
   Notcurses can be built without its multimedia functionality, requiring a
   significantly lesser set of dependencies.
 
-* All APIs natively support the Universal Character Set (Unicode). The `cell`
+* All APIs natively support the Universal Character Set (Unicode). The `nccell`
   API is based around Unicode's [Extended Grapheme Cluster](https://unicode.org/reports/tr29/) concept.
 
 * Visual features including images, fonts, video, high-contrast text, sprites,
@@ -214,7 +214,7 @@ to breaking under incorrect `TERM` values. If you're not using `xterm`, your
 
 * **Q:** Notcurses looks like absolute crap in `mosh`. **A**: Yeah it sure does. I'm not yet sure what's up.
 
-* **Q:** Why didn't you just use Sixel? **A:** Many terminal emulators don't support Sixel. Sixel doesn't work well with mouse selection. With that said, I do intend to support Sixel soon, as a backend, when available, for certain types of drawing (see [issue #200](https://github.com/dankamongmen/notcurses/issues/200)).
+* **Q:** Why didn't you just use Sixel? **A:** Many terminal emulators don't support Sixel. Sixel doesn't work well with mouse selection. Sixel tends to be horribly inefficient, and has a limited color palette. With that said, both Sixel and the Kitty bitmap protocol are well-supported.
 
 * **Q:** I'm not seeing `NCKEY_RESIZE` until I press some other key. **A:** You've almost certainly failed to mask `SIGWINCH` in some thread, and that thread is receiving the signal instead of the thread which called `notcurses_getc_blocking()`. As a result, the `poll()` is not interrupted. Call `pthread_sigmask()` before spawning any threads.
 
@@ -234,7 +234,7 @@ to breaking under incorrect `TERM` values. If you're not using `xterm`, your
 
 * **Q:** I only seem to blit in ASCII, and/or can't emit Unicode beyond ASCII in general. **A:** Your `LANG` environment variable is underdefined or incorrectly defined, or the necessary locale is not present on your machine (it is also possible that you explicitly supplied `NCOPTION_INHIBIT_SETLOCALE`, but never called `setlocale(3)`, in which case don't do that).
 
-* **Q:** I pretty much always need an `ncplane` when using a `cell`. Why doesn't the latter hold a pointer to the former? **A:** Besides the massive redundancy this would entail, `cell` needs to remain as small as possible, and you almost always have the `ncplane` handy if you've got a reference to a valid `cell` anyway.
+* **Q:** I pretty much always need an `ncplane` when using a `nccell`. Why doesn't the latter hold a pointer to the former? **A:** Besides the massive redundancy this would entail, `nccell` needs to remain as small as possible, and you almost always have the `ncplane` handy if you've got a reference to a valid `nccell` anyway.
 
 * **Q:** I ran `notcurses-demo`, but my table numbers don't match the Notcurses banner numbers, you charlatan. **A:** `notcurses-demo` renders several frames beyond the actual demos.