Log Message:
Update speedtouch to 1.3.1.

The main changes is to support revision 4 modems (silver cycle
helmet/beetle) and to use the threaded pppo3 if native threads are
available.

Tested on:
	- stringray by David Brownlee (abs@) and me
	- purple cycle helmet/beetle by David Brownlee
	- silver cycle helment/beetle by me