Bug 565656 – Add marks to scales
* gtk/gtkrange.[hc]: Add internal api to define 'stop values'
that have a little resistance when dragging the slider over it.
* gtk/gtk.symbols:
* gtk/gtkscale.[hc] (gtk_scale_add_mark): New function to add
a 'mark' to a scale, which will draws a tick, plus optionally
some text, and makes the value a stop value.
(gtk_scale_clear_values): Removes all marks.
* tests/testscale.c: Test for marks on scales
* tests/Makefile.am: Integrate it
svn path=/trunk/; revision=22149
