Hide build dir
Improve test coverage & remove redundant code
Automatically make registered patterns match from string start
Make 1 regex instead of a combination of regexes

And slightly fix it, adding test which it failed on:
numbers followed by var-like were incorrectly joined.
Only 1 trim instead of 2

With less chars; we're guaranteed to only have \n or space
by that point.
Minor cleanups/fixes

These didn't currently cause any issues, but needed fixing :)
Some more PSR-2 fixes
Specify type of array elements in phpdoc
Allow import conditions to be set
Impore test coverage for CSS minifier