Previously we used uniqid() here.
However this means that the behaviour is not reproducable, so
when uploading files into a "empty" folder, the folders name is
different.

If there would be a md5() hash collition, the deduplicate check
will spot this and append an index later, so this should not be
a problem.

Fix #6722

Conflicts:
	lib/private/vcategories.php

Now slugify is performed on whole filename (including extension). Changed method of adding index number (using regular expressions pathinfo() method removed).

fixing copy operation on mapper

indexing the full path exeeds the maximum index length for MySQL

this allows us to run unit tests on linux - necessary to enable easy regression testing

initial version of a local storage implementation which will use unique slugified filename on the local filesystem.
This implementation will only be enabled on windows based system to solve the issues around UTF-8 file names with php on windows.