Some work on input mapping
Changed some things
Some more changes.

ToDo: Make the GridView model use joypad_settings_mapping
Corrected the values in the input GridView model
Allow remapping inputs.

ToDo:
* Input settings are not saved when the window is closed
* The GridView is not updated when an input keybind is overwritten (You can end up with 2 keys apparently bound to "Return", but it's only an illusion).
Merge pull request #26 from Subv/uiStuff

Allow input mapping from InputSettings.qml