Release of Gambas 1.9.51

The database component is now case sensitive, and so some applications may break. The gb.qt and gb.gtk now share more code, especially the drawing routines that were moved to a dedicated common component. The features that cannot be common are put in the gb.qt.ext and gb.gtk.ext extension components.

The other main changes are:

There are anyway tons of bugfixes. See the ChangeLog for the details.