Bonus emits 2 signals depending on winning or loosing

In previous version only the signal done() was send in
both cases making it harder to follow up in the activities.
Replaced hard coded activity list by a config file

Now the list of activities are set in the file:
src/activities/activities.txt

There is no more need to change ActivityInfoTree.cpp when a new activity
is added.
Improved scaling ratio

Now set the ratio to be calculated on our base reference size of
800x520.
Added many scaling where needed using the ratio.
The result is much better on tablets where many images was too small.
Fixed exit upon leaving 2 times in the same activity

We had a signal connection from the menu to the activity on the home
button. But when entered a second time another connection is done thus
the home is called twice and triggers the application quit.

In the patch we now pass the menu to ActivityBase and it triggers the
home and dialog box display.
Fixed an error message on home and dialog click.
Added a script to create new activities.

Tu use it, go in the src/activities directory and run:
./createit.sh myactivity

It copies the files in the template directory and rename them
with the name of the requested activity name. The activity list
and the GCompris.pro are also updated so you can run the activity
immediately.
Ported colors activity.

Did not implemented the voice message.
Ported ballcatch activity
Minor, more usual syntax for MacOSX.
Improved colors activity to make it generic.

Now we can pass it the json dataset, the background image and
the item graphical size.
Ported instruments activity.

The sound is working on Android but not on desktop linux due to
a bug in Qt Quick (ogg does not play on linux).