new param 'user' for managing user variables
implement user variable management, also a bit of refactoring
add ability to load user hives that are not already in registry

more work on #3; still not sure how to do the unloading of user hives
correctly.
finish up auto (un)loading of user registry hives.

This should take care of #3, pending some test.
remove excess comments, make Win32API call style consistent
remove manifests directory. It has nothing in it.
make default broadcast_timeout 100ms.

Broadcasting doesn't even work when puppet is running in the background,
which it usually is, so there isn't any reason to be waiting 5sec per
window.
fix module name
make 'user' a namevar

Want to be able to create environment variables with the same name and
value but different user, so user needs to be part of the resource's
identity. (Wasn't quite done with #3 after all).
new tests for 'user' param
new features documented
update for version 2.0.0
fix a backslash escaping issue