Don't draw client console buffer past top of screen

Thanks @Pan7.
mint-arena: Make refEntity_t shaderTime be an int instead of a float

Converting time to a float results in precision loss at long uptimes.

This commit doesn't fix that, but should be possible to fix by only changing engine now.
Restore drawing a cut off client console line in 1920x1080

The text lines don't meet at top of the sceen in 1920x1080, restore
drawing a cut off line across the top. In 640x480 this line isn't seen
at all. This is still better then trying to draw twice as many lines
than are actually seen (the way it was before the last commit).
Merge remote-tracking branch 'mint-arena/master'