Support for YAML-TMLanguage

[scripthunter7]

Currently, this library can natively parse TMLanguage from JSON and PLIST formats.

I suggest extending these "natively supported" formats with YAML.

YAML is a convenient format for creating TMLanguage because:

• compact (no unnecessary curly brackets or tags)
• supports comments (useful for complicated regexps, for example)
• complicated regexps can be formatted to multiple lines, which helps improve readability

For example, GitHub Linguist also supports YAML-TMLanguage natively or TypeScript TMLanguage written in YAML

A possible (and the most simple) solution could be to use the js-yaml parser, although I'm not sure about this, since as I can see this library does not use external dependencies