.m currently clashes with Objective-C, and MUMPS is chosen before
Objective-C when creating .m files in Gist. Even if .mumps isn't a
legitimate MUMPS extension, I think we should change it anyway since
Objective-C is far more likely to be intended when a user uses .m

Added .podsl extension for Common Lisp language

Via comment https://github.com/github/linguist/pull/536#issuecomment-24046315

Add squirrel

Change YAML type to data

Yaml ain't Markup Language!

Added support for LFE (Lisp Flavored Erlang).

Rename Delphi to Pascal

Adding .x3d to the list of .xml extensions.

Adding .x3d to the list of .xml extensions: [x3d specifications] (http://www.web3d.org/x3d/specifications/x3d_specification.html)

Add the ".cljx" file extension to the list of Clojure languages.

Some people start writing portable Clojure/Clojurescript code and use
the ".cljx" file extension for that. This is driven by this project:

https://github.com/lynaghk/cljx

Remove unused else

Add .nqp to the list of Perl file extensions

Added Volt language

Add COBOL language support

Add alternative Logtalk source file extension

Add OpenGL Shading Language.

Add the .rbxs extension for Lua files

COPYING is added to excludes as a file that contains copyright informati...

This is the language used for writing OpenGL shaders, which are becoming much more mainstream lately.