#18 file-type menu screwed up on setup

[Sam Richards]

The first time filmgimp is launched, and the
.filmgimprc file is setup
(or the pluginrc file to be more exact), the menu for
file-type in the image-save option is repeated twice,
the first set are all enabled (incorrectly), the second
set are correctly flagged according to the image bit-depth.

This is not critical, but it could be confusing.

Sam.