A lot bugfixes for ext-cache and deprecated files removed:

A lot bugfixes for ext-cache and deprecated files removed:
- Fixed a problem that no cache file was removed and later used after another registration
- Fixed a problem with CSS mode: cache files got created and removed, now only allowed in 'mode 0'
- Fixed a problem with CSS mode again: When ext-cache is registered css.php raises a missing array element 'revision'
- Some double quotes to single quotes converted
- Deprecated (ext-repair vs. ext-menu) includes removed
- Other minor improvements like more debug messages in debug-mode