size/grid/clear increment preferences

[alexwarrior]

Implements a way of supporting the size/grid/clear increment preferences again. There are preferences in the preferences dialog for choosing how much sizes and such are incremented/decremented when a keystroke is used. A lot of internet tutorials and such for geda mention these preferences as well. But, these preferences go unused, as +5/-5 values appear in the (g)pcb-menu.res files. So this patch allows a special +pref/-pref argument to be passed for the delta argument of the relevant actions so that these preferences can work again.

[Ineiev (ineiev)]

hi,
I've just rebased the patchset against current GIT master, refactored it a little bit, added Lesstif handles to enter increment preferences and pushed it here:
http://repo.or.cz/w/geda-pcb/dti.git?a=shortlog;h=refs/heads/alexwarrior-increments

Thanks,
Ineiev

[DJ Delorie (djdelorie)]

See Bug sf-1741732

[Andrew Poelstra (asp11)]

I will take a look at this when I am done cleaning up the unit-handling code.

Note that Alex Warrior's original patch is incompatible with my recent changes.

[Andrew Poelstra (asp11)]

I have split the dialog into metric/imperial sections, and implemented all its functionality.