SWC-673: change to alpha processor rather than widget
add inline syntax, and fix preview
add inline math equation test
small
must move util method to sharedmarkdownutils since it is used on both the server and client
from code review
Merge pull request #526 from jay-hodgson/SWC-673-alpha

Swc 673 alpha: Synapse markdown processor support for math blocks and single line span
SWC-790 Deleted renderer approach for the urls
SWC-790 Retrieve new features
SWC-790 Added an extractor for use in parsers that need to protect content from others