[SQUASH ME] hc: implement helper functions to disable HC dynamically
[SQUASH ME] core: reply for config
[SQUASH ME] sixlowpan.core: less error-prone api replies
[SQUASH ME] sixlowpan.tests: disable HC for fragment sending tests
[SQUASH ME] sixlowpan.core: remove error checking in inline initializers
[SQUASH ME] sixlowpan.iphc_cbuf: remove invalid return in DEVELHELP path
[SQUASH ME] sixlowpan.tests: print pktbuf on pktbuf related errors
[SQUASH ME] sixlowpan.tests: start header compression tests