Since double-click is usually used to open things, don't use it to enter
edit mode, use platform-specific keyboard shortcut instead (Return, F2,
etc).
Add context menu duplicating available actions, resembling that of Mac
client. This includes new "only check selected" action.
Speed up DND/priority change for large numbers of files at once. Make
DND/priority toggling more natural: if both parent and its child are
selected, only act on parent (with all its children following).
Use simple tokenization instead of splitting the file path into
QStringList for each item. Don't expand each added item separetely
during population/update. Don't expand all the items but just up to the
point where parent has more than one expandable child.
Also, fix items order by sorting items after population/update. Fix
sorting by size on systems where uint64_t != quint64.
Split FileTree.{h,cc} and FilterBar.{h,cc} files so that each class
is in its own file.
This breaks translations (some classes got renamed => context changed),
to be fixed by next commit (along with Tx sync).