Modified inline parsing to not use `ref` parameters.
Temporary backtracking in emphasis parsing for when a `*` or `_` is a literal character inside emphasis.

Fixes `*_*` but not `*_*_`.
On 4.5 force inline of `bchar`
Fixed the issue described in jgm/stmd#51

Implemented a stack of emphasis openers that are reviewed every time a
potential closer is discovered.
Note that two more tests are failing - those are actually not conforming
to the rules described in the specification.
Emphasis stack is now a queue (since openers have to be revisited left-to-right).
Changed version number
Updated perf data
Merge remote-tracking branch 'knagis/master'
fixed merge conflicts