"New colors last"; place colors at end of New

New option to place color palette items at the end of the "New"
dialog, rather than at the beginning.  Useful for when users
would want to pick from a set of Starters and/or Templates,
e.g., in a school or museum environment.

Available via command-line option "--newcolorslast", and
config file setting "newcolorslast=yes".  (And anti-option to
override config file settings, "--newcolorsfirst" and "...=no",
which represents the original behavior, which continues to be
the default).

Suggested by Bernard Verhaeghe.

src/parse.gperf

@@ -123,6 +123,8 @@ mirrorstamps,        POSBOOL(mirrorstamps)
 mixedcase,           NEGBOOL(only_uppercase)
 mouse,               NEGBOOL(keymouse)
 native,              POSBOOL(native_screensize)
+newcolorsfirst,      NEGBOOL(new_colors_last)
+newcolorslast,       POSBOOL(new_colors_last)
 orient,              MULTI(rotate_orientation)
 outlines,            NEGBOOL(dont_do_xor)
 papersize,           MULTI(papersize)