Fixes a slew of compiler warnings and turns on "warning as error" in the scons build.
diff --git a/src/gmock-internal-utils.cc b/src/gmock-internal-utils.cc
index 196ec74..4c51ec0 100644
--- a/src/gmock-internal-utils.cc
+++ b/src/gmock-internal-utils.cc
@@ -64,7 +64,7 @@
     if (isalnum(*p)) {
       if (starts_new_word && result != "")
         result += ' ';
-      result += tolower(*p);
+      result += static_cast<char>(tolower(*p));
     }
   }
   return result;