* gegl/buffer/gegl-buffer-allocator.c: (gegl_buffer_alloc),
(gegl_swap_dir): added swapdir lookup function, with empty GEGL_SWAP
~/.gegl-0.0/swap is now used, set up a symlink to /tmp or /var/tmp if
you want that kind of behavior. GEGL_SWAP=RAM causes gegl to use
the old behavior of swapping to RAM.
* gegl/gegl-init.c: (gegl_init)
(gegl_exit): use gegl_swap_dir() to get at swap location for cleanup.
(gegl_post_parse_hook): modified default module search path to
include ~/.gegl-0.0/plug-ins/, also add a dummy Makefile to this dir
if none exist.

svn path=/trunk/; revision=2019