[Amforth] AmForth Weekend 5

[<ho...@tj...>]

Fellow AmForthers,

This is AmForth Weekend 5. It has been a while.

## Reference card

The reference card on amforth.sourceforge.net has been updated to 
reflect the current compilable core. Stack patterns, categories and 
descriptions are extracted almost automatically from comments in the 
assembler source. This has required some editing of comments in the 
codebase, and is pass one, with more passes to come I am sure.

## AVR8 + amforth-shell.py

Nigel provided a patch for amforth-shell.py fixing command line 
completion. Thank you. It should also now work on macOS. The lack of 
support for the ATmega328PB was also raised. IIRC the ATmega328PB is the 
last of the classic ATmega series, and thus the last mcc the avr8 
codebase can support without a rework. A ~decade ago "blast from the 
past" overview [1] Given they are available on some inexpensive nano-ish 
format boards and offer a bit more than a ATmega328P it would be nice to 
support them beyond binary compatibility with the ATmega328P.

## Prebuilt hex files for AVR8

There is now appl/prebuilt which includes the two sizes of hex files for 
each of the development boards covered. See 
https://amforth.sourceforge.net/TG/prebuilt.html for more details. 
Creating the hex files is a makefile driven process that uses Mark's 
fork of avra (Thank you). Replicating and customising the build should 
be straightforward.

## RISC-V + ARM

See https://sourceforge.net/p/amforth/mailman/message/59322865/ and the 
mailing list in general. Going forward I propose moving the current 
RISC-V + ARM elements to an archive directory within the existing 
Sourceforge repo.

Best wishes,
Tristan

## COMMITS

r2463   website (prebuilt + refcard) and doc related .asm edits
r2464   patch to amforth-shell.py to fix tab completion (Thank you 
Nigel)
r2465   alignment patch to risc-v/macros.s (Thank you John)
r2466   add appl/prebuilt directory

[1]: https://hackaday.com/2016/01/26/bye-bye-atmega328p-hello-328pb/