Documentation updates from Enoch for the shell utility

git-svn-id: svn://svn.code.sf.net/p/amforth/code/trunk@1423 fd1c0b69-5d68-47f5-910c-86182ebb6ecd
My usual local changes
amforth-shell.py bugfix. skips already uploaded #include files.
According to #include-once state #include file would skip an already uploaded file.
Introducing soft interrupts handler.
New directive: #include-once

if activated upload a given file only once even if requested multiple times.
Default setting is OFF and there are no persistent information stored to
hand over to other shell sessions. Patch by Enoch.

git-svn-id: svn://svn.code.sf.net/p/amforth/code/trunk@1424 fd1c0b69-5d68-47f5-910c-86182ebb6ecd
New word: u2/


\ unsigned division by 2.
\ -1 u2/ . gives 32737
\ -1 2/ .  gives -1
\ -1 2 / . gives 0

Suggested by Rafael (as assembly word).

git-svn-id: svn://svn.code.sf.net/p/amforth/code/trunk@1425 fd1c0b69-5d68-47f5-910c-86182ebb6ecd
Merge remote-tracking branch 'git-svn'
Getting ready for github.
rewrite readme