This refactoring is driven by the need to be able to do true queued RPC calls
(where each successive call uses the result of the previous).
Currently, such queueing of requests is done by assigning them special "magic"
tag numbers, which are then intercepted in one big switch() statement and acted
upon. This (aside from making code greatly unclear) effectively makes each such
queue a singleton, because state passing is restricted to global variables.
We refactor RpcClient to assign an unique tag to each remote call, and then
abstract all the call<->response matching with Qt's future/promise mechanism.
Finally, we introduce a "RPC request queue" class (RpcQueue) which is built on
top of QFutureWatcher and C++11's <functional> library. This class maintains
a queue of functions, where each function receives an RPC response, does
necessary processing, performs another call and finally returns its future.
If open file dialog is a native one, setting the layout will do more harm
than good. Specifically, on Windows with Qt 5 the dialog becomes completely
unusable.
This has a couple of benefits: 1) it is clearly visible to the user that
the list is filtered (doesn't display all the torrents) even when filter
bar is hidden, 2) doesn't lead to filter bar controls being shifted to
the left/right as when "Show:" label text changes.
Disable "Open Folder" and "Verify Local Data" actions for magnets in
Torrent menu. If more than one torrent is selected, "Verify Local Data"
is enabled but only non-magnets are verified if activated.
Add a few sanity checks when opening folder, just in case.
We don't currently (if ever) provide context help, so the button is
useless. Moreover, on Windows 10 it's even larger than before and
sometimes title text doesn't fit because of it.
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.
