gdi_graphic_context_provider & cl_line_loop

[huntercool]

This patch adds support for CL_Draw:box()

There is currently a bug in the code which draws the third and forth line of the box invisibly.

Perhaps an expert may take a look at this patch.

Thank you.

[rombust]

Patch applied. (modified slightly)

I think the bug is caused by the line draw routine not drawing "down to up" correctly