Added rst files
rename .xhtml to .rst (but don't change contents yet)
replace .rst files with Koblaid's versions
remove doc_rst/ subtree
clean up using-foolscap.rst
docs: cleanup copyable, failures, flappserver
docs: clean up logging, schema, serializing
docs: clean up specifications/*
Makefile: remove lore-based docs rules
docs: replace Lore with .rst

Many thanks to Koblaid for starting this process four years ago. I'm
sorry it took me so long to merge your work!