Rework how configuration is handled a little bit, addint a d_is_location
member, which keeps track of whether the config directive is wrapped in
a Location block. This is that when we're in a location, we can omit
running the map_to_storage phase and not touch the fs at all during a
request. This has a potentially unusual side-effect of disabling all
fs-based Directive config parts, this is yet-to-be-documented.

Also remove trailing blanks from a lot of lines - this makes it a mess
of a commit, but oh well.