Viewport bugfix, tracking code

Demo:
-viewport tracking code (commented)
-removed extraneous viewport restoration

Altimeter:
-viewport tracking code (commented)

Main:
-frame tracking code (commented)
graphics implementation supports

graphics:
-tracks viewport stack rather than (wrong) Boolean
+allows viewport restoration to previous
-drawing scaled image now uses OpenGL methods

Viewport:
-new utility class to hold and display viewport area
Merge branch 'master' of https://github.com/SEPRGroup/SEPR4Project