v4.3.0 release

Rusthon to languages list for syntax highlighting: #2001
NewLisp language support: #1143
Disambiguate Matlab, Objective-C, Mathematica, M, and Mercury: #1652
Specify ace_mode for OpenSCAD: #2025
GAP and Scilab disambiguation: #2030
Better samples for Pascal: #2031
Better ASP syntax highlighting: #2037
Support Vim and Emacs modelines for syntax highlighting #2041
Grammar for Liquid templates: #2044
Update Powershell grammar: #2047
Update Swift grammar: #2048
Add .cp as valid C++ extension: #2055