- Added support for `Size` and `Format` options and slightly improved format detection from canRead().
- Removed conversion to ARGB32 on load (improved performace with RGBA images).
- Added result checks on writing.
With this MR, all plugins have minimal support for options.
Two main tests: read the file and compare to a given image (loaded from
png), and write a file out and compare to a previously-written image.
The write test in particular is kind of fragile, but it should help
catch some errors where a code change was not intended to affect the
output of the plugin.
Tests are included for all the writable formats, as well as every
readable format that GIMP can write to (and so I could easily get an
example of).
REVIEW: 115430
