+2.1:
+ Added 4-bit link estimator to CTP in lib/net/4bitle
+ Added DIP dissemination protocol in lib/net/dip
+ Added FTSP time synchronization service in lib/ftsp
+ Added TOSThreads library in lib/tosthreads
+ Added SafeTinyOS support with 'safe' make option
+ Added support for 802.15.4 T-Frames through 'tframe' make option