Replace inline with _FORCE_INLINE_ in short methods.
Remove unused and redundant method no_area() as we already have has_no_area().
Add grow_individual() grow_margin() and expand() to Rect2i.
This allows more consistency in the manner we include core headers,
where previously there would be a mix of absolute, relative and
include path-dependent includes.
Rémi Verschelde
qarmin
lupoDharkael
Aaron Franke