Significant updates

Wrote time sheet parser that ingests and validates all semi-structured
data. Next step is to interpret left styles as dates, so that hours can
be parsed into a time entry object.

Updated HTML parser to more completely filter out unhelpful data, and to
internally build the array of doubles (data and left style).

Toolchain upgrades

Migrated to `venv` for the Python module dependency(ies).

Added `README` to begin documenting the process.

Initial commit