Added a go.mod to make it a Go module, which was long overdue.

Characters that are not Betacode are passed through beta.Writer unalt…

…ered now.

The exported string constant beta.Ignored that had previously contained all the
ignored characters has been removed because it has lost its (always misguided)
purpose.

Fixed a typo where capital V converts to an at-sign instead of digamma.

Now sports an updated README, huzzah!

Ignore most characters appearing in annotated texts

Allow Parsing Perseus Project Betacode

Initial release on GitHub