Add incremental CCM authentication processing

CCM is only meant for packet mode where the length of the input is known in
advance. Since it is a packet mode function, CCM only had one function that
performs the protocol.

However, incremental authentication is usefull in some usecases. It also
ensure some kind of coherencies when processing with a given authentication
mode or another. To achieve this aim, this commit adds the following functions:
    ccm_init()
    ccm_add_aad()
    cm_add_nonce()
    ccm_process()
    ccm_done()
    ccm_reset()
as well as the data structure
    ccm_state

Change-Id: I5225a42bb098708c4af07518b561bb00f85bc243
trim trailing spaces
add missing pointer checks
also run testvectors on new CCM API

[skip ci]
ccm test: add missing AAD
Merge branch 'pascal-brand-st-dev/ccm' into develop

This closes #55