Add TOC nesting level option to hoedown_html_renderer

Closes #19.
Merge commit '3d9ca45d6721a3ea8ec90844eff745ef430b8c69'
Support toc_nesting_lvl
Fix hoedown_buffer_printf on MSVC

Apparently "vsnprintf is included for compliance to the ANSI standard"
doesn't actually mean it's ANSI compliant.

Closes #21.
Merge commit '78f042d990a7850ea1a658a997e8c299538eddf1'
Checking in changes prior to tagging of version 0.05.

Changelog diff is:

diff --git a/Changes b/Changes
index dcc5592..86fc97e 100644
--- a/Changes
+++ b/Changes
@@ -2,6 +2,11 @@ Revision history for Perl extension Text-Markdown-Hoedown

 {{$NEXT}}

+0.05 2013-10-01T02:15:31Z
+
+    - MSVC fix comes from hoedown upstream.
+      (Reported by charsbar++)
+
 0.04 2013-09-30T11:03:15Z

     - CONST() macro conflict with MinGW.