Removed some stuff from mpvhandler

Fixed up some things and put in Qt::QueuedConnection for the PlayFile signal. Though this should fix any possible clashing thread issues it still hasn't fixed the issue. I'm going to look into a way to make sure all functions in mpv get called on the same thread, this might be the issue--similarly with the playlist manager.
mainwindow.ui: layout finished with minor issues
Added AboutDialog.ui
MainWindow.ui: interface is complete
Added placeholder JumpDialog.ui & InfoDialog.ui
InfoDialog.ui: setup basic controls
Many additions, coding the UI

Cleaned up and commented all the connections. Fixed up the openUrl dialog functionality and created classes for the other uis. Added many mpv-related commands to handle the new ui functionality.
More additions to the UI

Brought the about ui back, not entirely sure why I accidently deleted it. Put in code for it.
Added functionality for OnlineHelp
Extended playlistManager and put in comments in the header file like my other header files.
Made some of the dialogs use signals and slots instead of events (like I did with mainwindow).
Added functionality of playlist-related buttons

Took a little while but now instead of using the playlistWidget's list because of some complications with that list, we have another QStringList list which we easily load to the playlist list with playlist->addItems(list);
Shuffling is done with std::random_shuffle from std::algorithm, it just shuffles the existing list, this should be added as a simple button at the bottom of the playlist like the rest of them.
Removed SettingsManager as only QSettings is necessary

Implimented some basic settings which work quite well and simply at the moment. Will naturally add more as things come up and many more when a settings dialog is created.
Added Show in Browser support

Also put in jumpdialog, when the gui is created it can be coded, once it's returning the correct values it'll implicitly work with the mainwindow.
Merge branch 'master' into mpv_playlist

Conflicts:
	Baka MPlayer/mpvhandler.cpp
	Baka MPlayer/mpvhandler.h
	Baka MPlayer/playlistmanager.cpp
	Baka MPlayer/playlistmanager.h
	Baka MPlayer/windows/mainwindow.cpp