Memory usage optimisations: `Server::generateMultiStatus()` - support Iterator as `$fileProperties` and also support objects as items of `$fileProperties`; `Server::getNodesForPath()` - don't iterate over collection of children, return Iterator instead; `ObjectTree` class - limit size of a cache
BIG-4045: use sys_get_temp_dir() rather than hardcoding "/tmp"
Merge pull request #1 from bc-petrkotek/BIG-4045

Memory usage optimisations