Added Apoorv Upreti's GSoC2013 work: visual test suite.

See visualtest/README.txt for details.

visualtest/src/mischelper.c

@@ -0,0 +1,28 @@
+/**
+ * \file mischelper.c 
+ *
+ * Source file with miscellaneous helper functions.
+ */
+
+#include <SDL_test.h>
+
+void
+SDLVisualTest_HashString(char* str, char hash[33])
+{
+    SDLTest_Md5Context md5c;
+    int i;
+
+    if(!str)
+    {
+        SDLTest_LogError("str argument cannot be NULL");
+        return;
+    }
+
+    SDLTest_Md5Init(&md5c);
+    SDLTest_Md5Update(&md5c, (unsigned char*)str, SDL_strlen(str));
+    SDLTest_Md5Final(&md5c);
+
+    /* convert the md5 hash to an array of hexadecimal digits */
+    for(i = 0; i < 16; i++)
+        SDL_snprintf(hash + 2 * i, 33 - 2 * i, "%02x", (int)md5c.digest[i]);
+}