COAP_CT_ style defines for the content types are deprecated in favour of
COAP_FORMAT_ style defines. COAP_FORMAT_ is expanded to include any
missing content type that was available with COAP_CT_.

Replaces all occurences of COAP_CT_.* with COAP_FORMAT_.*

msp430_types.h is included implicitly if needed by sys/types.h
native also needs sys/types.h, no idea why it was excluded originally..

This replaces the netif->state accesses in netif::recv with a netdev call
and the new netif RAWMODE flag

Adds a gnrc_netif specific rawmode flag to indicate that the netdev
device is configured in raw mode. This flag is kept in sync with a
possible flag in the netdev device and should only be modified via the
setter call.

gnrc_sock_recv used to duplicate functionality of gnrc_ipv6_get_header,
but additionally checked whether the IPv6 snip is large enough.

All checks are now included in gnrc_ipv6_get_header, but as most of them
stem from programming / user errors, they were moved into asserts; this
constitutes an API change.