Create mist branch from Thingsquare Mist 1.1.0

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>

Version 2.6

Version 2.6 release candidate 0

Update makefiles to git release tags and directories

Move 16-bit integer conversion operations into functions, as is done …

…already with 32-bit ops.

Update to Contiki version number 2.4

-> 2.3

Bumped version number to 2.2.3

Bumber version number to 2.2.2

2.2 -> 2.2.1