Fixed incorrect rendering of open bracket inside codeblock

See test cases for details.
Removed duplicated calculations
Two codeblocks separated by empty lines should be one codeblock

See test cases for details.
Don't interpolate inside codeblock

See test cases for details.
Don't inline inside codeblock

See test cases for details.
Merge pull request #8 from ndpar/codeblock-fix

Codeblock fixes