- In order to avoid warning "Missing braces around initializer ...", braces has been replaced by double braces in all initialization lists.
	- http://stackoverflow.com/questions/13746033/how-to-repair-warning-missing-braces-around-initializer
- Unused attributes and methods has been removed from class Viewport.
- Added compilation flags -Wall, -Werror and -pedantic-errors.
- Unfinished methods relative to rotations around a pivot has been commented out in order to avoid compilation warnings/errors until I decide to finally implement them.