new formula: xplanetFX 2.5.24

xplanetFX is a program that manipulates Xplanet renderings with lighting effects using ImageMagick.
Fixing Caveat Text
Removing gnu-sed default name option

by replacing all occurrences of "sed" in script to "gsed"
Commit addressing all discussed issues...

1. Using EOS in the caveat section
2. Using gsed instead of sed
3. Using "if build.with?" instead of "unless build.without?"
4. Confirming X11 is a required dependent
reflecting change in pygtk formula
Updating to xplanetFX 2.5.25...

which checks for gsed.  Also removed the " sed" to " gsed" inreplace as  aresult.
removing gnu-sed path addition in caveats
xplanetfx: add 2.5.25 bottle.