Added comments, organized includes
Refactoring at UsiCore root

Organized includes.

Removed:
AppWindow.addGeneralSettings()

Renamed:
app.authReqManager() -> httpManager()
ModuleInterface.preinit() -> initialize()
ModuleInterface.getMainController() -> getController()
Removed "m_" from member variables

Added:
SplashScreen.showStyledMessage to remove repeating arguments call
Adjustment on network & settings classes

- Added UsiException class to be base for all custom exceptions
- Merged isAvailable and isUnblocked into assertMalAvailable which
throws NetworkException
- removed "m_" prefix on members
- added comments
- restyled pointers
- QueryData is now a Map<QString,QString>

Renamed:
SettingsFormatJson -> JsonSettings
RequestManager -> HttpRequestManager
RequestManager.lastOperationAborted -> RequestManager.lastRequestAborted
SettingsManager.*DeleteOnExit -> SettingsManager.*Temporary
Fixed creeping bug that caused application crashes and network failures.

Internal QNetworkAccessManager got deleted in BlinkCore destructor.
Also a race condition was present in BlinkCore and BlinkXmlParser caused
by queued receiving of QNetworkReply, resulting in segfaults.
Also, application now synchronizes Blink retrieval at starting and
blocks input when before exit chores are being performed.