eForth for cheap STM8S gadgets

The STM8 assembler integrated into SDCC works well, but it's rather outdated, and poorly documented. I now updated the GitHub Wiki page to share some insights.

Also note that I now found a workaround for passing literals for conditional builds into the tool chain: use the "-I" option for defining the search path for ".include". It's not pretty, but it works. Code changes are in the making.

I just updated the GitHub Wiki: some outdated stuff was removed, and some useful information on the W1209 was added.