CSCI580_Fall_2014: 0.1 version of Homework 3. Not finished, some
problems of drawTriangles.
CSCI508_Fall_2014: 0.2 version of Homework 3. Solve the problem of Xiw
(Previously I mistake Xwi as Xiw, and after I prove it I find my
mistake). Prove that the all node in a tri in world space will stay in
the tri in perspective space, if we do homo. in X,Y,Z
CSCI580_Fall_2014: 1st version of Homework3. Meet minimum requirement,
no other GUI action
CSCI580_Fall_2014: 1.1 version of homework 3. Add addaction function