#37 [PATCHES] Fix Contiki build and replace ECC implementation by micro-ecc

[Markus]

Building the tinyDTLS example with Contiki master failed for me. The attached patches 1-3 fix those issues (and do a bit of cleanup).

The second part of the patchset (4-5) replaces the old ECC implementation by micro-ecc (https://github.com/kmackay/micro-ecc) which increases the speed at least for AVR based devices from about 30-40 seconds per step to something around 2 seconds.