rockspec files are used by [Luarocks](https://luarocks.org/), the
most prominent package manager for Lua. Despite the different file
extension, these files are actually Lua files and should be syntax
highlighted as such.
For what it is worth, Neovim also does the same thing that I am doing in
this commit. They recognize both ".lua" and ".rockspec" as being Lua
files (and no other extensions, as far as I know).
This fixes a bug in how the Lua scripts handle new comment lines.
Currently if we have a comment that is indented, when we add a new line
it inserts the `--` prefix before the automatic indentation.
```
--ABC
-- XYZ
```
After the fix, it correctly inserts the comment prefix after the
indentation:
```
--ABC
--XYZ
```
The solution I used is inspired by the ruby.kak script.
Correctly indentint on "end" keyword seems very hard,
it is simpler to remove it. And we already insert "end"
in ruby-insert-on-new-line hook, so the removal shouldn't
hurt too much.
1. Deleted back-tick strings which are not a valid Dart syntax
2. Added string interpolation for ${}
3. NOT adding string interpolation for $var as this is considered a bad practice
This commit adds highlighting characters other than the first with red color helping to get immediate feedback of the syntax error.
This helps those who come from languagles like JS where single quotes also denote multi-character strings.
Adding highlighting for string interpolation inside double-quoted strings and character literals inside single-quotes.
Avoiding string interpolation in the form of $var as this is considered bad practice.
* bring colors more aligned with upstream solarized implementations
(e.g. vim, emacs)
* tweak rust syntax
* add more details, like operators, highlighting certain traits and
types from std, etc
* remove certain highlighters, like user types. This has the effect
of just highlighting almost the whole code base one color, and
wasn't really correct either. CamelCase for types is only convention
