* Remove SIMD option, the logic in the Makefile was inverted, so it was
enabled anyway.
* Add GEXIV2 option description
* Fix plist for not-enabled RAW option
* Don't install examples
Disable docs for now, will be enabled when 0.3.0 is released.
Convert to option helpers, mention why the UMFPACK support doesn't work.
Make parallel installable with gegl 0.2 by renaming the installed executable
and example dirs.