Allow slashes in unquoted prop values (unless immediately followed by >)

[jviide]

This pull request modifies the parsing logic (and adds related tests) so that slashes in unquoted property values are allowed. For example <abba prop=val/ue><//> parses to h('ab', { prop: 'val/ue' }). The exception is when the / is immediately followed by > - <abba prop=value/> parses as a self-closing element h('ab', { prop: 'value' }).

Slashes in tag names and property names will still self-close the element. For example <ab/ba prop=value> parses to h('ab', null), and <abba pr/op=value> parses to h('abba', { pr: true }).

The regular build size grows by 8 bytes (588 B -> 596 B) and the mini build size grows by 9 bytes (417 B -> 426 B). The performance doesn't seem to be affected, based on test:perf runs with V8 on MacOS 10.14.6.

Closes #106.

[jviide]

Added a commit that updates the main README.md to reflect the slighly increased size of the mini build.

[developit]

LGTM!