Fix end source position for nested or indented fenrced code blocks.

Improves on earlier fix to #141, which only worked for code blocks
flush with the left margin.

Author: jgm

lib/blocks.js

@@ -325,7 +325,8 @@ var blocks = {
                     ln.slice(parser.nextNonspace).match(reClosingCodeFence));
                 if (match && match[0].length >= container._fenceLength) {
                     // closing fence - we're at end of line, so we can return
-                    parser.lastLineLength = match[0].length;
+                    parser.lastLineLength = parser.offset + indent +
+                                             match[0].length;
                     parser.finalize(container, parser.lineNumber);
                     return 2;
                 } else {