+ codeblock cannot interrupt a paragraph
+ separate handling of code blocks indented vs fenced
  + fence does not terminate indented code block
  + handle various forms of fences:
     - ` vs. ~
     - different fence lengths
     - no mixed fences
     - fences inside fenced region
+ handle (and require) escaping of [ ] inside references (method arguments)

fixes https://github.com/eclipse-jdt/eclipse.jdt.core/issues/2824