Docs: move docs into docs/
Misc: fix warning about autoloading haml
Files: add support for spaces as tabs
Test: improve taskpaper parsing tests
Tests: add node unit tests
Parsing: try to be less dependent on on-demand parsing of tags
Parsing: parse tags in parse-time
Tasks: deprecate #plain_text in favor of #text
Allow setting tasks as done using 'x'
Docs: document the GitHub format
CLI: use proper unicode characters
Release v0.5.0