#1646 Add Twig support

[Mustang]

I am a user of Notepad2-mod (http://xhmikosr.github.io/notepad2-mod/) which is based on Scintilla, after a plea to the project maintainer to add a Twig syntax highlighting scheme, apparently it's not possible because this isn't implemented in Scintilla yet.

Perhaps this Notepad++ config is helpful starting point: https://github.com/Banane9/notepadplusplus-twig

[Neil Hodgson]

Support for new languages is normally contributed by those that use the languages or build products based on the languages.