* move taskchampion-lib to src/tc/lib, remove the rest
* update references to taskchampion
* Use a top-level Cargo.toml so everything is consistent
* apply comments from ryneeverett
* move doc/misc to top level, add READMEs
* Move docs -> doc/devel
This also consolidates the _three_ documents describing (differently)
how to build Taskwarrior into a signle document.