2) Replaced "early" (before LM) checkouts with "late" (inside LM) ones.
3) Removed the mutex protection that's no longer necessary.
Note: the new LM contains some future code (currently commented out) which will be enabled and tested after the Alpha release.
1) Separate process and owner blocks. Multiplex blocking signals via single blocking thread.
2) Enable direct in-process AST delivery.
3) Drop PREVENT_OWNER_STARVATION code as not compatible with the new LM structure.
4) Synchronize LM using its own mutex instead of SCH.
5) Implement wakeup'n'remap code for waiting owners.
6) Add more debugging points for memory remaps.
7) Cleanup and style.
Hopefully, this attempt is more POSIX-friendly than my previous one.
