plan for absolute positioning

the element is removed completely from the normal flow and is positioned relative to it's containing block

in Layout.layoutChildren() it should no use the absolute child when calculating
where to start the next block after the abs child.


the containing block is not the immediate parent block, but the closest parent
block with position: absolute or the viewport (perhaps i should default the
body to position: absolute?)

for relative and static elements the containing block is the immediate parent block.

for position: fixed the containing block is the viewport only.

i will need to modify the context object to contain a reference to the viewport
block and to most immediate containing block.
they will need to be stored in terms of the current translate.
create a method c.translate(int,int) to translate the graphics, plus the viewport reference and the containing block reference.
intialize containing block to 0.
change all g.translate into c.translate

create translatetocontainingblock and translateFromContainingBlock
create translatetofixed and translatefromfixed