feat: replace code_block indent spaces with ZWSP (#15)

Author: galaxian85

lib/rules_block/code.js

@@ -30,7 +30,7 @@ module.exports = function code(state, startLine, endLine/*, silent*/) {
   state.line = last;
 
   token         = state.push('code_block', 'code', 0);
-  token.content = state.getLines(startLine, last, 4 + state.blkIndent, true);
+  token.content = state.getLines(startLine, last, 4 + state.blkIndent, true, true);
   token.map     = [ startLine, state.line ];
   token.position = pos;
   token.size = endPos - pos;