[CM] Two minor bugs in snd-8 preferences menu

[Bill Schottstaedt]

> if the sonogram colormap is not set!ed in 
> .snd_prefs_guile, a segmentation fault occurs the 
> first time you try to open the preferences dialog. 

I can't get this to happen in any version of Snd.

> At the next try the menu is opened but the options are 
> listed only up to sonogram colormap, which is broken 
> and unsettable. If you save the preferences, the 
> colormap is given the value -1, which happens to have 
> the same effect described above. 

The value of -1 is not legal -- it should generate an
error message.  I don't set it to -1 anywhere.

:(set! (colormap) -1)
colormap: no-such-colormap: (-1)


What version of Snd is this?  (what does ./snd --version
print out?).  Also, if possible, what is the stack trace
at the point of the seg fault?