[Bug-gnubg] file selection code moved to gtk_file_chooser

[Christian Anthon]

Hi all,

I have submitted some code, which moves the remaining file selection
code to gtk_file_chooser. This was done in a few places already, but
that code has been rewritten as well to give a more unified look.
Apart from the obvious changes, the main difference is the use of
default paths for different formats, which has been obsoleted.
gtk_file_chooser uses bookmark for that purpose, but a few default
folders is definable through settings/options/other.

Christian.
-- 
"I can't promise that I'll try. But, I'll try to try." -- Bart