Use Win32 named mutex instead of file lock.

Need to avoid problems when clcache incorrectly terminated (e.g.
by process killing). In that case lock file may remain in the file
system and will not allow other instances of clache start.
Also, mutex should work a bit faster, since we eliminate disk and
filesystem access.
Extract main() function to ease script testing
Initial implementation of daemon infrastructure from python side.
First working implementatino of building through cacodaemons.

Without caching yet. Needs a refactoring.
Implement caching file hashes and compiler paths.

Fix some errors with not properly set env. variables when compiling
through daemon.
Support of value for daemon count.
Add compiled launcher to repository to ease setup on TeamCity agents