“grail-home-page” apparently actually means “grail-help-root”
Fix syntax for catching a set of exceptions
Clean up and fix presumed errors in PrefsPanel module

* Class name is computed from panel name; stored version was never used
* Fix “reloading” parameter and module path removal
* Unpack sequence objects to avoid indexing the wrong element
Unused “error” parameter; “sys.exc_value” only defined in exception handlers
re.split() arguments seem to be the wrong way around
Looks like unpack_item_array() was being called on wrong object