more windows doc updates
monospace flags
mention mtimes
make unittest match module name
more minor manual touchups
move pool docs down under "more details"

The earlier section is a tutorial-style overview.  The latter section
is for side features like phony rules and header dependencies.  Pools
fit in with the latter.
slightly smaller subsections
include mtimes in deplog explain
always use output timestamp for deps

Using the timestamp of the .d file was wrong.  It can be written
at a different time than the output, and it is immediately deleted
after parsing; only the output remains for subsequent timestamp
comparison purposes, so always use the output's timestamp.  (This
is how the code worked on Windows already.)
build ninja itself in deps mode

Hopefully will help flush out bugs.