minor, replace Gcompris by GCompris.

Global replace in po files.
lang, fixed a python exec error case

If we have an error in the startup sequence a
variable was used non initialized.
lang, fixed startup sequence in remember level mode.

The ready button was bypassed in remember level mode.
administration, layout improvement

the module labels was too large. replaced them by
tooltips.
lang, fixed 'back to last level' mode.

fixed call to bonus so that we properly log
success to each exercise.