rework classloader

- make it available in config
- always use classloader, no manual require
- compatible for future composer alternative
use autoloader in tests
get rid of $min_libPath
Merge branch 'autoloader' into dev

Conflicts:
	min/builder/index.php
	min/config.php
	min/index.php
	min/lib/Minify/Loader.php
	min_extras/cli/rewrite-uris.php
	min_extras/config.php
	min_unit_tests/_inc.php