Make ALUGrid compile with gcc 4.0.2.

Therefore had to add missing include set in stlheaders.
Also added missiong virtual Destructors for classes with virtual functions.
And some () for truth check when also assign, exmaple gitter_tetra_top.h
795.


git-svn-id: https://dune.mathematik.uni-freiburg.de/svn/alugrid/trunk@414 0d966ed9-3843-0410-af09-ebfb50bd7c74