win32: fix `win32-in-place' target on existing tree
paint-by-numbers: fix path construction

Syntaxes of filesystem paths and module paths are not the same
under Windows.
mzcom: fix installer
mzcom: set mzobj interface version to bogus value, for now

MzCOM and its build process need some sort of overhaul, but
it's on the backburner for now.
raco setup: better tracking of provides in database

Keep track of the out<n>.sxref timestamps, so that `raco setup'
can detect when the database is out of sync (instead of assuming that
it's always in sync with out<n>.sxref files).
move release notes in appropriate packages

A collection declares release notes with a `release-notes' field in
"info.rkt".

The "doc" directory is now populated exclusively by generated content,
instead of having a static "release-notes" directory (and a "keep-dirs.rktd"
file to record the static directories).
fix `server' target
fix `distro-build' package