Make all paths absolute
There are bunches of cases internally where it would make sense to have all the paths in Tor be absolute, and none (that I can think of) where taking paths as relative to the CWD actually helps us.
We could find things that should be absolute and make them so piecemeal, but that would invite missed cases. Better, we we could just turn all paths into absolute paths when we read them in from the configuration.
(See #1101 (moved) and #4881 (moved) for earlier work here. Marking this for 0.2.4.x, since 0.2.3.x is approaching feature freeze.)