Fixed Copy::listContents return type on non existing dir.
Fixed more listContents return types and tests for them
Fixed return type of FilesystemInterface::readAndDelete to account for failed reading.
Fixed return type for FilesystemInterface[update,updateStream]
Corrected AbstractCache::getMimetype docblock with inheritdoc
New line ending fixes.
Corrected read interface has return type to account for unknown (cache)
AbstractCache docblock duplication removal.