gsPoissonAssembler.h: Removed the unneeded virtuals, added the fullMatrix() function.
gsPoissonAssembler.h: Removed the unneeded virtuals, added the fullMatrix() function.

git-svn-id: 6b1c4fe79111c0bc0cce83313250759594f8984b@3893 e128ff1e-fa79-4151-a8cb-522299a2c450

filiatra/gismo,filiatra/gismo