Fixing a regression: have BIFs AND nice error reports!

Built-in functions were simply prepended to the Stylus file being
converted, the nice errors patch worked because we stopped prepending
them which caused the built in functions to all fail!
Added a .gitignore file for easier switching between master & test branches
Merge branch 'master' into test-environment

Conflicts:
	.gitignore
Removed an obsolete comment

That error was resolved in a previous commit.
Added more test cases.