comments on possible optimization strategies
a comment on possible optimization
Merge branch 'master' into opt

Conflicts:
	src/grid/cg_level_connected.F90
	src/grid/cg_list_bnd.F90
slightly optimized prolongation by avoiding one copy of an array
comment on performance
fixed mistake in a comment
Merge pull request #64 from gawrysz/opt

Optimization (PRACE PA1757)