• int MLReady(MLINK link) tests whether there is data ready to be read from link.
• Analogous to the Mathematica function LinkReadyQ.
• MLReady() is often called in a loop as a way of polling a MathLink connection.
• MLReady() will always return immediately, and will not block.
• You need to call MLFlush() before starting to call MLReady().
• See Section 2.13.14.