[DB] Add: DB thread
Revert "[DB] Add: DB thread"

This reverts commit fc09d3a62eb15bf593dab6080f7e09bc954ba606.
Revert "Revert "[DB] Add: DB thread""

This reverts commit 0d5f9a04c7334b5a7ec64af4a6678735f1509207.
[TCP] Delete unnecessary thread
[DB] Delete unnecessary thread
[APPLICATION] Inherit CApplication from QApplication.
[UI] Change UI solution from QuickQT