Fix for inconsistent redirection to message threads list when pressing
BACK from sending message from Contact view. Also proveded mechanizm
to help switching back to previous App, when some App call window
from another App.
Stack plus minimum tests added
Updated to master
Removed useless or adressed TODOS
Constants name applied
Renamed searchModel to searchRequestModel
Review applied
We should remove legacy window names
Bell names fixes
1. Prepare Pure and Bell specific `Application`
classes and add them to `app` target:
- `products/BellHybrid/apps/Application.cpp`
- `products/PurePhone/apps/Application.cpp`
2. Update `CMakeLists.txt` files.
3. Move `ApplicationBell` implementation to Bell-specific
`Application` class and remove `ApplicationBell` files.
4. Change Bell apps parent classes from `ApplicationBell`
to Bell-specific `Application` class.
5. Rename `Application` to `ApplicationCommon` in the rest of the files.
