Clipping is broken

[jacobly0]

One comment says the clip region is inclusive, however the default clip region (0, 0, lcdWidth, lcdHeight) is exclusive.

[adriweb]

As said on IRC, since the current function relies on a pair of points instead of point + w/h, a solution to this is to introduce: void gfx_SetClipRect(int xmin, int ymin, unsigned int width, unsigned int height); as we cannot break compatibility with older versions.
(However, should the default clipping window be fixed to be (0, 0, 319, 239)?

[mateoconlechuga]

Or just make things exclusive. This is really only broken for lines at the moment, and it doesn't really have an affect on output.

[mateoconlechuga]

Partially fixed and tested with 7d3e9d7, need to run a few more tests though

[mateoconlechuga]

Good to go :)