The idea is to consider assemblers as "runtime" apps instead of
placing them in the "bootstrap" section of the blocks. These apps
will be used for much more than bootstrapping.
Moved its documentation to doc/asm.txt and made its code blocks
more compact.
As I wrote in my "Clarify signed-ness" commit, "0 <" is broken.
Also, made this unit a bit more compact. The RC2014 stage1 can
really use some breathing room...
