Changed delayed_send(), timer, and wall clock
- The delayed_send() function now forwards message envelopes to the timer which puts them on its (now non-global) message queue
- Wall clock now sends itself a message delayed by one second to tell itself when to update and display the time
Now using RTX_ERR and better error message
Merge pull request #1 from edinkha/setpriorityproc

Merging the Setpriorityproc branch into Master.
Added user input checking and fixed bug in wall clock
- Now checking if the user entered invalid text at the end of the expected input
- Fixed wall clock bug where entering an invalid %WS command would stop the clock if it was running
Added command line checking for non-whitespace characters after the expected input of a command.
FINALLY FIXED THE DAMN POPPING/UART BUG :D

I moved the pUart declaration so that it wasn't global (this wasn't the
issue, just a bit of cleanup)...

The issue had to do with us printing / releasing memory before we
toggled the IER_THRE bit, for some reason. I emailed Irene to see if she
knew why it'd be happening, but in the meantime, I'm just glad it's
fixed >.<
Removed TODO lines in k_memory
Updated Doc
Hard faulting on stress test
Pushed utils file
Fixed hard fault(s)

Note: Can't use k_procs in user procs -- causes user/kernel level
conflicts, hence the hard faults.
Changed i = 10 to ++i just to be consistent
Moved Proc A so that it can register commands with KCD
Moved Proc A under wall clock by Nathan's request for better housekeeping
Added a base-10-only version of itoa to utils.c
Improved performance of itoa.
Stuff we changed in the lab today
Cleaned up and simplified things.
- Removed unnecessary casts and uses of `sender_id`
- Got rid of the "subscript out of range" warnings
Added preemption to timer interrupts.
- Normalized use of the g_switch_flag across the timer and UART i-processes
- After these changes I am no longer seeing the "Should not get here!" message in the UART i-proc
- Also noticed performance improvement in printing characters in the simulator
Merge branch 'master' into stress-test