[LyX/master] Fix bug #8746: Images have to have alt tags.

[Richard Heck]

commit 30d3fcd640c180407a8a1db7679cca42eaa9e0c1
Author: Richard Heck <rgh...@lyx.org>
Date:   Wed Jun 12 17:24:59 2013 -0400

    Fix bug #8746: Images have to have alt tags.

diff --git a/src/mathed/InsetMathHull.cpp b/src/mathed/InsetMathHull.cpp
index 7059914..d03eca9 100644
--- a/src/mathed/InsetMathHull.cpp
+++ b/src/mathed/InsetMathHull.cpp
@@ -2206,7 +2206,7 @@ docstring InsetMathHull::xhtml(XHTMLStream & xs, 
OutputParams const & op) const
                        string const tag = (getType() == hullSimple) ? "span" : 
"div";
                        xs << html::CR()
                           << html::StartTag(tag)
-                                << html::CompTag("img", "src=\"" + filename + 
"\"")
+                                << html::CompTag("img", "src=\"" + filename + 
"\" alt=\"Mathematical Equation\"")
                                 << html::EndTag(tag)
                                 << html::CR();
                        success = true;