Move swap/cache and temporary files out the GIMP user config dir:
libgimpbase: add gimp_cache_directory() and gimp_temp_directory()
which return the new default values inside XDG_CACHE_HOME and the
system temp directory. Like all directories from gimpenv.[ch] the
values can be overridden by environment variables. Improve API docs
for all functions returning directories.
Add new config file substitutions ${gimp_cache_dir} and
${gimp_temp_dir}.
Document all the new stuff in the gimp and gimprc manpages.
app: default "swap-path" and "temp-path" to the new config file
substitutions. On startup and config changes, make sure that the swap
and temp directories actually exist.
In the preferences dialog, add reset buttons to all file path pages.
(cherry picked from commit a29f73bd9a)
Some gimprc properties' default values depend on the machine where
"make dist" in run. We had an ugly hack in place to force
(num-processors 1) in the installed system gimprc and its manpage, but
were still leaking "tile-cache-size" and "mypaint-brush-path".
The files are generated by the hidden options --dump-gimprc-system
and --dump-gimprc-manpage which exist only for this purpose.
In gimpconfig-dump.c, special case the three properties in
dump_gimprc_system() and dump_gimprc_manpage() to output constant
default values for "num-processors" and "tile-cache-size" and
output @mypaint_brushes_dir@ in "mypaint-brush-path" which can
be replaced at configure time.
Also introduce etc/gimprc.in so @mypaint_brushes_dir@ can actually be
substituted for the installed system gimprc.
This was hard-coded to what I guess was a personal prefix (commit
368c7c0511), which is obviously wrong. This has to be constructed at
compilation and the man must mirror whatever is the actual installation
path of mypaint-brushes package.
Since we have many themes now, this new name better indicates that it
is meant to follow your desktop theme settings.
Also it will likely not remain the default theme.
It's now either $XDG_CONFIG_HOME/$gimpdir/2.9 or directly $gimpdir,
depending on whether $gimpdir is a relative or absolute path. Build
the resulting string in configure and put it into the manpage_gimprc
variable so it can be used in the manpage sources.
