File extension (.gex) may still change if anything better is proposed.
This format is currently just a compressed archive containing the
extension data (plug-in, brushes or whatever) and the metadata file.
For now, opening such file will simply install it as a new extension,
keeping all file permissions and structure. Of course in the future, it
will have to trigger a confirmation dialog.
Currently the compression used is zip, which is just a first draft. This
is not a decisive choice as well. We could use some tarball compressed
in whatever other compression algorithm. I use libarchive as a new
dependency to support unarchiving as it seems to be a common library
(and since it is already used by AppStream-glib anyway, this doesn't add
any actual dependency, just make it direct).
We currently have brush and pattern I/O code in both the core and
plug-ins. This commit starts removing plug-in code in favor of having
one copy of the code in the core, much like XCF loading and saving is
implemented.
Add app/file-data/ module with file procedure registering code, for
now just with an implementation of file-gbr-load.
Remove the file-gbr-load code from the file-gbr plug-in.