Empty lines are stripped from comment-blocks too early in the process

[erikhagreis]

For our project we are implementing a custom parser which parses multiline fields with markdown formatting.

Empty lines within markdown denote separation between paragraphs and are therefore important to retain.

I believe this is the part of the code that strips empty lines in the _dss.parse function:

// Remove extra whitespace
block = block.split('\n').filter(function(line) {
    return (_dss.trim(_dss.normalize(line)));
}).join('\n');

For other usecases like markup they could be stripped but for flexibility I think it should be left to the custom parsers instead of the initial 'prep' cycle in DSS.