override dump method to prevent empty classmaps being generated.
improve phpdoc.
drop abstract class.
Merge branch '7.x-pimple' into 7.x-autoload
move classmap generator class.
move bootstrap override to a vendor package.
Merge branch '7.x-pimple' into 7.x-autoload

Conflicts:
	composer.json
add comments to gitignore.
Merge branch '7.x-autoload' into 7.x-symfony