Some steps to a better usability with compounds. Improvements in drawing of...

Some steps to a better usability with compounds. Improvements in drawing of compounds: Edges of compounded surfaces in the CAD are hidden, only the collection of compounded surfaces is shown, the single surfaces are hidden. The draw command is called for the compound and then piped to the underlying surfaces. Can be controled with commandline parameter 'compound_only'. Further steps will follow in near future (high order meshes using compounds etc.).