rlutil.h - line 577 - Warning: Converting of "size_t" to "unsigned int", data loss possible.

On line 577 change:
`unsigned int len = str_.size();`
to:
`unsigned int len = static_cast<unsigned int>(str_.size());`

On line 580 change:
`unsigned int len = strlen(str);`
to:
`unsigned int len = (unsigned int) strlen(str);`
