Fixed #192.

The C and JS implementations were not registering blank lines
after atx headers for purposes of tight/loose list calculation.

Exmaple:

    * item
    * # block1

      ## block2

1 files changed, 4 insertions, 0 deletions

diff --git a/js/lib/blocks.js b/js/lib/blocks.js
index fd76b15..65c2c46 100644
--- a/js/lib/blocks.js
+++ b/js/lib/blocks.js
@@ -266,6 +266,9 @@ var incorporateLine = function(ln, line_number) {
         case 'HorizontalRule':
             // a header can never container > 1 line, so fail to match:
             all_matched = false;
+            if (blank) {
+                container.last_line_blank = true;
+            }
             break;
 
         case 'FencedCode':
@@ -279,6 +282,7 @@ var incorporateLine = function(ln, line_number) {
 
         case 'HtmlBlock':
             if (blank) {
+                container.last_line_blank = true;
                 all_matched = false;
             }
             break;