Show symbol and emoji after it's name in auto-completion list

[zufuliu]

In issue #289, LaTeX input method is implemented, one can type math symbols and emojis by their name using LaTeX like abbreviations (e.g. \sum for ∑, \:smile or \:smile: for 😄): type the abbreviation (or select one from auto-completion list), then press Tab (also called Tab completion in some other editing environments). See https://docs.julialang.org/en/v1/manual/unicode-input/ and https://github.com/iamcal/emoji-data for all supported LaTeX and emoji sequences.

However, currently only the symbol/emoji names are shown on auto-completion list, it would be better to show also the symbol/emoji (like GitHub emoji drop-down list). For sorting purpose, symbol/emoji can only be placed after it's name.

This currently can not be implemented: the auto-completion list is rendered with legacy GDI, which doesn't support colored emoji, and has bugs on rendering math symbols (see XhmikosR/notepad2-mod#121 and other bug reports).

The upstream Scintilla ticket https://sourceforge.net/p/scintilla/bugs/2179/ is about implementing DirectWrite for auto-completion list, once that is done, we can implement this.

[lifenjoiner]

currently only the symbol/emoji names are shown on auto-completion list

Just got an alternative option for Win10 users: Win + . to use the OS input method program 🤐😬

[zufuliu]

Emoji input can be disabled by set EnableLaTeXLikeEmojiInput (in LaTeXInput.h) to 0, this will make Notepad2.exe 26KiB smaller.