new formula: xplanetfx 2.5.26

xplanetFX is a program that manipulates Xplanet renderings with lighting effects using ImageMagick.

run gdk-pixbuf cache update in post install with conditional
xplanetfx 2.5.26 update
adding PATH to wrapper script
and fixing dependency options
xplanetfx: add 2.5.26 bottle.

Closes #28785.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>