clean up support for installing extensions, split legacy stuff from functionality like it should be, add support for exts_classmap, add missing docstrings
make self.name and self.version properties in Extension, to fix compatiblity for multiple inheritance with EasyBlock *and* Extension
provide a copy method for EasyConfig instances
copy cfg, ext and options instead of just keeping references to them, fix use of inappropriate try-except
cosmetics
Merge pull request #416 from boegel/extension_easyblocks

make required changes for supporting ExtensionEasyBlock