minor change in comments of AdvDiff solver in ModelPDE test


git-svn-id: svn://svn.code.sf.net/p/elmerfem/code/trunk@6783 04224531-1f84-46d8-96ce-875b9e37dce3
Added the ModelPDE to the modules directory to be included in the pre-compiled solvers.


git-svn-id: svn://svn.code.sf.net/p/elmerfem/code/trunk@6784 04224531-1f84-46d8-96ce-875b9e37dce3