Update for itex2MML 1.38

Add support, in the LaTeX export, for blackboard bold
digits and lowercase latin letters. If these are
present, LaTeX will
   \usepackage{mathbbol}
N.B.: this uses the stmaryrd font for blackboard bold
letters, instead of the msbm font.
Tests included. (Yes, you need to update itex2MML as well.)

app/views/wiki/tex.rhtml

@@ -4,6 +4,9 @@
 \usepackage{amsfonts}
 \usepackage{amssymb}
 \usepackage{amsthm}
+<%- if @tex_content =~  /\\mathbb\{[^}]*[a-z0-9]+[^}]*\}/ -%>
+\usepackage{mathbbol}
+<% end -%>
 \usepackage{graphicx}
 \usepackage{color}
 \usepackage{ucs}