Srishan

Disallow normalization and improve robustness against invalid input

1

## Changes - Reject B.S. dates (via the Date() function) that would have normalized. (fixes #79) - Add upper bound checks for date limits, don't know why this wasn't there...

Collection of my thoughts around date normalization in Nepcal. #79 reported a bug where a B.S. date that overflowed into the next month would not be rejected by Nepcal. The...

The std lib `tabwriter` doesn't handle ANSI escapes, so we've to resort to non-optimal output. The `tabwriter` algorithm seems simple enough to recreate.