Fix source bugs

The source can't be edited
GrayScale from Lilemon's Work (and correct by Neckara)
Threshold fixed by Lilemon
Add commentaries and fix a little bug (InputText's label wasn't hidden)
Fix numbering
Add commentaries.

Before refactoring : 5 000 lines.
Afters commentaries : 8 000 lines.

Past year group : < 3 000 lines (with our commentaries).
relecture des com's