[raster] Switch to routine Int instead of Short. This is mostly cosmetic and removes a few casts, plus Short is promoted to Int in calculations anyway. * src/raster/ftraster.c (Vertical_Sweep_Init, Vertical_Sweep_Span, Vertical_Sweep_Drop, Horizontal_Sweep_Init, Horizontal_Sweep_Span, Horizontal_Sweep_Drop, Draw_Sweep): Mostly s/Short/Int/ and remove casting.