Renamed Colors.qml in FindIt.qml

Since it is used externaly to create other actvities, it is
best under its original name FindIt.qml.

Added some protection to let it useable even without audio in
the dataset.
Fixed reference to intrument images

Now use FindIt instead of Color for the base activity name.
Ported advanced colors.
Readded missing includes.
Core, no more add empty activities in the model

In development mode we are used to remove actvitities from the
main Makefile. It was annoying to have empty  activities in the
main menu.