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/Makefile.am b/include/Makefile.am
index c125691..0a300a8 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -82,6 +82,7 @@
                        osmocom/gsm/mncc.h \
                        osmocom/gsm/prim.h \
                        osmocom/gsm/l1sap.h \
+                       osmocom/gsm/oap.h \
                        osmocom/gsm/protocol/gsm_03_40.h \
                        osmocom/gsm/protocol/gsm_03_41.h \
                        osmocom/gsm/protocol/gsm_04_08.h \