docs: remove blank files to keep site link layout tidy
docs: eradicate loathed toml for friendly yaml

- both github docs and pandoc display sensibly when yaml is found
docs: consolidate into a single dir
docs: update docs on docs
build: add doc clean target
docs: use tags for taxonomies
docs: add to menu bar and order via weight
docs: reflow overview.md
doc: backquotes
build: update erlang.mk
channel: add opaque channel_zero/1 test
swarm: tidy up gproc case
options: add use_minimum_options/0 to use in datagram parser when receiving packets on channel 0
channel: add get_swarm_id/1 to help look up smarm options via channel during unpacking
datagram: teach handle/1 to cope with replies on channel zero or a supplied channel
datagram: this hack is a good place to stop for the weekend
datagram: return whole endpoint, not just channel
datagram: split handle/1,2 into separate named functions
message: swap debug call for returning all info via error
datagram: handle the messages