don't call xcache_clear_cache on clearOpcodeCache() in case admin auth is enabled for xcache in php.ini
don't use xcache in case admin auth is enabled in php.ini - this can cause issues
Do not define xcache_unset_by_prefix() if it does not exist.

The defined function is not compatible with the function provided by xcache
because it does not honor the prefix parameter. Thus defining it like this is
a bad idea.
Allow usage of xCache variable cache if xcache_unset_by_prefix() is present.
Clear xCache OpCode cache instead of variable cache in clearOpcodeCache().
xcache_unset_by_prefix() returns feedback, return it.
Add link to XCache API in class documentation.
xCache -> XCache
Make it clear that log message is about the XCache opcode cache.
Do not mention php.ini, it may be defined in xcache.ini or so.
Added support for extra backends

Somebody had forgotten "OC_User::setupBackends();"...
fix the legacy popup to make calendar settings look nicer
No decimal points for Kilobyte and Byte #5371.
enable more tests
Symfonys addCollection() with multiple arguments is deprecated, fix deprecation warning
Only run memcached tests if server is available.
fix shadow size and arrow position
preserve 3rd party values in  in the Session destructor
Ensure memcached extension is there before attempting to create an instance.
correctly mark app management active