added basic inline XML without attributes
added support for attributes in inline XML
added support for XML comments in inline XML
added support for inline character entities
fix forward URL references
optional angle brackets surrounding link URL's
began adding official Markdown tests
tabs can be used in lists
correct handling of multi-line list items
added correct tabs to spaces translation for preformatted code blocks
corrected link syntax to allow for a possibly empty URL
fixed reference style links
fixed strong&em using triple '*'/'_'
added methods for returning Scala XML objects