Added new FV heat transfer model and two test cases

git-svn-id: https://thermopower.svn.sourceforge.net/svnroot/thermopower/trunk@279 80daafeb-7430-0410-91d5-8b30b0bbd841
Changed name of Thermal.HeatTransfer package to Thermal.HeatTransferFV for better namespace handling (non backwards compatible!!)

git-svn-id: https://thermopower.svn.sourceforge.net/svnroot/thermopower/trunk@280 80daafeb-7430-0410-91d5-8b30b0bbd841