Remove execute rights from `test.js`
Update retext, gemoji
Add nlcst-emoji-modifier as a dependency
Remove nlcst-to-string from dependencies
Add retext-inspect to dependencies
Add `EmoticonNode` to module

This update adds a new `EmoticonNode` (which subclasses
`SymbolNode`) which houses emoji and gemoji.

Additionally, this update adds better support for detecting
emoji after the sentence's terminal marker.
Add flat badges to `Readme.md`
Update changelog for 0.4.0-rc.1
0.4.0-rc.1