Improved descriptions

git-svn-id: https://thermopower.svn.sourceforge.net/svnroot/thermopower/trunk@224 80daafeb-7430-0410-91d5-8b30b0bbd841
Improved RankineCycle and BraytonCycle examples

git-svn-id: https://thermopower.svn.sourceforge.net/svnroot/thermopower/trunk@225 80daafeb-7430-0410-91d5-8b30b0bbd841