Lib.SpanRuleEscapeSourceEscaped character: HTML special characters, e.g. &, <, etc., are translated to &, <, etc. The following characters should be escaped by backslash in markdown.
[ ] \ ` * # _ { } ( ) + - . !include SpanRule.STry to apply a rule. The first parameter is the (recursive) function that parses a string as a span list.