import oap message parsing / encoding from openbsc.git; AGPL->GPL

In the process, also:
* Change the license from AGPLv3 to GPLv2-or-later;
* correct spelling of 'sysmocom' to lowercase;
* add '2016' to the copyright;
* rename to osmo_*;
* add API docs;
* add logging category DLOAP: define id and add to internal_cat;
* redirect all oap.c logging to DLOAP.

A unit test will follow in a subsequent patch, since it needs a minor tweak for
decoding of boolean values.

The related openbsc change-id is I2f06aaa6eb54eafa860cfed8e72e41d82ff1c4cf.

Tweaked-by: Neels Hofmeyr
Change-Id: If5099e60681a215e798b6675f21813f26769c253
diff --git a/include/osmocom/core/logging.h b/include/osmocom/core/logging.h
index cc3919b..1ca348a 100644
--- a/include/osmocom/core/logging.h
+++ b/include/osmocom/core/logging.h
@@ -93,7 +93,8 @@
 #define DLGTP		-9	/*!< GTP (GPRS Tunneling Protocol */
 #define DLSTATS		-10	/*!< Statistics */
 #define DLGSUP		-11	/*!< Generic Subscriber Update Protocol */
-#define OSMO_NUM_DLIB	11	/*!< Number of logging sub-systems in libraries */
+#define DLOAP		-12	/*!< Osmocom Authentication Protocol */
+#define OSMO_NUM_DLIB	12	/*!< Number of logging sub-systems in libraries */
 
 /*! Configuration of singgle log category / sub-system */
 struct log_category {