- don't make duplicated edge.
- a node should only fall to the following one if it doesn't jump
  to another node. now fixed.
removed extra whitespace
- use real number as spillCost.
- removed extra whitespace.
- added SP.
- removed extra whitespace.
- some node in the graph may have no edge associated with, but we
  still need to add them to the mappings between temp and node.
- added call to procEntryExit2.
- added main.
- uses new temps for saving/restoring calleesaves.
- added instructions for saving/restoring callersaves.
- args are now saved to new temps
- fixed munchStm on CJUMP(T.NE..)
- removed whitespace.
- added code for spilling and rewriting program.
- break should have type UNIT
- fixed case for let - it now collects all decs
- fixed case for for loop - it should use Le, not Lt to test upper bound.
- fixed for loop body.
- removed extra parameter "exps" from transDec.
- added code for handle spilling.
- removed whitespaces.
- fixed simpleVar
- fixed subscriptVar and fieldVar, they shouldn't use T.MEM
- fixed ifelse
- added code to generate externalCall
- fixed sequence.
- removed whitespaces.
- removed whitespaces.
- used simplecolor.sml and tiger-apple.lex.sml