TYPO3 Core

Since TYPO3 core packages (extensions) are independently
published and might be installed in arbitrary file locations
in the near future, referencing assets in package A
from a CSS file package B will likely not work.

Therefore all assets that are referenced from a CSS
file are now moved to the package that contains this CSS file.

Also references of assets in CSS that already were located
in the same package are cleaned up to not assume a hard coded
path name (breaking out of Resources/Public directory).