xbee.wait_read_frame() has no time protection #29

What steps will reproduce the problem?
1. Distant ZigBee (or, open a virtual (non-conected) serial port
2. Open a ZigBee object and run wait_read_frame()
3. The program will not respond anymore

What is the expected output? What do you see instead?
The output could be a integer, or anything else.

What version of the product are you using? On what operating system?
Gentoo Linux. python-xbee 2.0.0

Please provide any additional information below.
I did an implementation, but I would like you take a look on it.