Added type conversions to fix compile errors

Added two type conversions that were missing in order to fix some
compile errors.

Engine/source/core/strings/stringFunctions.h

@@ -150,11 +150,20 @@ inline U32 dAtoui(const char *str, U32 base = 10)
    return strtoul(str, NULL, base);
 }
 
+inline U16 dAtous(const char *str, U32 base = 10)
+{
+   return strtoul(str, NULL, base);
+}
+
 inline F32 dAtof(const char *str)
 {
    return strtof(str, NULL);
 }
 
+inline F64 dAtod(const char *str)
+{
+   return strtod(str, NULL);
+}
 
 inline char dToupper(const char c)
 {