Add signals and improve the scheduler
* Begin implementing unix signals
* Catch userspace exceptions (still some work left to be done on page
faults)
* Add the vdso. For now it only has the signal trampoline
* When mapping virtual memory as not present intermediate page levels
will be marked as present
* A whole bunch of work on the scheduler in general (see diff)
* Some smaller stuff here and there
31 files changed,
894 insertions,
185 deletions