edknrc needs some array size checks to avoid mysterious crashes

[dworogers]

In edknrc, if $MXREG is not set properly or at least large enough, the code just stops with no explanation. It would be useful to have a check at the start of execution that $MXREG >=$MAXRADII*$MAXCDOSE+1 and that

$MAXRC >= MAX($MAXRADII,$MAXCDOSE)
$MAXRADII+1 > $MAXRADII
$MAXCANGLE >= $MAXCDOSE-1