Fixed RF#29704: header IDs on atx headers don't work correctly with trailing hashes
Fixed RF#29647: Abbreviations with non-word first character at start of text lead to exception
The quotation mark entity &quot; now gets converted to its character equivalent when entity_output=as_char
Fixed test_files.rb to generate correct tests in case a html.19 or htmlinput.19 is present
Made option handling more robust by automatically converting names to symbols
Hopefully fixed encoding problem of GH issue #38

kramdown dnow transcodes the source to UTF-8 for internal use and
transcodes it back after conversion.