Fix OrEmpty semantics

Turns out if a parses the empty element successfully OrEmpty a did precisely what we don't expect, that is parse the empty element as an a 🤦

Hotfix: make sure decode . encode = id

Turns out sometimes (in particular in Text elements) whitespace does matter...

0.2.0.0

Merge pull request #2 from EggBaconAndSpam/rewrite

Major rewrite / cleanup