Changed H1, H2 and P element to bool.
Simplified MarkdownElement type by using function type.
Separated files.
Renamed package.
Removed exported unused constants.
Removed unused option OutDir.
Added usage print.
Added H2-H6 parser.
Added a test file.
Added multi-line H1 and H2 parser.
Removed Options and separated ParseFile and Parse.
Added gitignore.
Supported close atx-style headers.
Reversed order of header evaluation and ignored space after header marks.