Fixes initialiseGLUT function call

- Function call to initialiseGLUT has been fixed.
Adds setPixel function

- Shortcut method setPixel added.
Adds setPixel and initialiseGLUT calls

- Function calls to setPixel and initialiseGLUT have been added to the
ParseLine function.
Fixes initialisePixelStore function

- The initialisePixelStore function now refers to the global variables
for scene dimensions.
Fixes glutMainLoop call

- glutMainLoop can only be called from main(). This has been fixed with
a workaround. Ideally, this should be called once the scene dimensions
have been extracted.