namespaces: use namespace object instead of dictionary
This isn't as bad as the diff seems, it only looks like scary. In this patch,
we use the 'namespace' object instead of accessing keys in a dictionary.
This required the 'templatename' and 'names' method to change their
implementation. Later, we will remove these functions entirely due to a better
api.
ERROR: FIXME: This is a known failure of filelog.size for data starting with \1\n
OK.