Rearrange proc.h and proc.c to get our action-packed spreads back (mostly).  They also make sense in this order, so it's not just for page layout.

Re-re-arrange bootasm and bootother.  We can't get bootasm and bootmain on the same page, but this will make them easier to flip between.

I totally misunderstood the even/odd spec.  Add some docs, remove my 'left+' hack, and orthogonalize left/right versus even/odd so you can specify them independently.

Slight simplification of copyuvm.  We could simplify other things now that processes are contiguous, but we'd have to think harder about the error paths.

Remove the stack guard page.  Processes are now contiguous from 0 to proc->sz, which means our syscall argument validation is correct.  Add a pointer validation test and remove the stack test, which tested for the guard page.

Our proc.c alignment is perfect.  Since ksegment/usegment went away, we get a column back, so we get our two action-packed spreads.

Swap bootmain.c and bootother.S.  This puts the whole boot process on one spread, though it separates the two asm files.

We don't use lesp/lebp and using them at all from C would be fraught with peril.  Keep resp/rebp, but fix their code style.

kinit() knows about end and PHYSTOP
map all of kernel read/write (rather than r/o instructions)
thanks, austin

do not keep sorted contiguous free list

Fix for gdbstub argument change in qemu 0.11.  Rename qemu-gdb-nox target to qemu-nox-gdb because you frequently want to add the gdb part, but rarely the nox part.