============= module Raster ==================
Raster image support.
==============================================

============= struct raster ==================
Raster defines raster (bitmap) image.
==============================================
width:1..2147483647
height:1..2147483647
format:int
depth:1..32
palette:table
lines:table of data
source_format:id
source_data:data

===== func cast {d:data like "BM"} -> raster =======================
Cast BMP data to raster.
====================================================================
sys_func#37

===== func cast {d:data like hex "89504e470d0a1a0a"} -> raster =====
Cast PNG data to raster. 
====================================================================
sys_func#35