* app/gimprc.c
* app/gimprc.h
* app/ink.c
* app/paint_core.c
* app/preferences_dialog.c: Now the perfect-mouse-tracking
normally enabled by pressing MOD1 is a preferences option,
and MOD1 inverts the affect.
* app/ink.c: Mildly tweaked the default brush size/range for
my own twisted sense of esthetics. Forgive me.