remove redundant search for assembler modules; use Configuration::get_assemblers instead.
Change assemblers to a hash instead of an array.

This also means we can check for the existence of the requested
assembler directly instead of looking for a match.
Don't rewrite the path for the bin in the actual module: save the find_bin for the end.
Find the binary using Configuration.pm at the last minute.
init_module doesn't initialize anything so am switching it to check_module
do a quick check to make sure we're not reinitializing for no reason.
just a simple reindentation.