Simplify allocuvm/deallocuvm to operate in a contiguous memory model.  This makes their interface match up better with proc->sz and also simplifies the callers (it even gets the main body of exec on one page).

Rearrange vm.c so it's in logical order and prints nicely.  Shorten a few functions in uninteresting ways to make them fit.

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.