src: port openBSC over libosmo-abis

This is a big patch that ports openBSC over libosmo-abis.
Sorry, the changes that are included here are all dependent
of libosmo-abis, splitting them into smaller pieces would
leave the repository in some intermediate state, which is
not desired.

The main changes are:

- The directory libabis/ has been removed as it now lives in
  libosmo-abis.

- new configuration file format for nanoBTS and HSL femto, we
  need to define the virtual e1_line and attach it to the OML
  link.

- all the existing BTS drivers (nanoBTS, hsl femto, Nokia site,
  BS11 and rbs2000) now use the new libosmo-abis framework.

- use r232 input driver available in libosmo-abis for bs11_config.

- use ipa_msg_recv instead of old ipaccess_read_msg function.

- delete definition of gsm_e1_subslot and input_signal_data.
  These structures now lives in libosmo-abis.

Most of this patch are deletions of libabis/ which has been
moved to libosmo-abis.

This patch also modifies openBSC to use all the new definitions
available in libosmocore and libosmo-abis. In order to do that,
we have replaced the following:

- DINP, DMI, DMIB and DMUX by their respective DL* correspondences.
- SS_GLOBAL by SS_L_GLOBAL
- SS_INPUT by SS_L_INPUT
- S_GLOBAL_SHUTDOWN by S_L_GLOBAL_SHUTDOWN
- SS_INPUT by SS_L_INPUT
- S_INP_* by S_L_INP_* sub-signals
- E1INP_NODE by L_E1INP_NODE vty node

This patch has been tested with:
- one nanoBTS
- the HSL femto with the examples available under libosmo-abis
- BS11 with both dahdi and misdn drivers.
diff --git a/openbsc/src/libbsc/abis_nm.c b/openbsc/src/libbsc/abis_nm.c
index a41414a..027a263 100644
--- a/openbsc/src/libbsc/abis_nm.c
+++ b/openbsc/src/libbsc/abis_nm.c
@@ -43,7 +43,7 @@
 #include <openbsc/abis_nm.h>
 #include <openbsc/misdn.h>
 #include <openbsc/signal.h>
-#include <openbsc/e1_input.h>
+#include <osmocom/abis/e1_input.h>
 
 #define OM_ALLOC_SIZE		1024
 #define OM_HEADROOM_SIZE	128
@@ -114,6 +114,26 @@
 				   "OML");
 }
 
+int _abis_nm_sendmsg(struct msgb *msg, int to_trx_oml)
+{
+	struct e1inp_sign_link *sign_link = msg->dst;
+
+	msg->l2h = msg->data;
+
+	if (!msg->dst) {
+		LOGP(DNM, LOGL_ERROR, "%s: msg->dst == NULL\n", __func__);
+		return -EINVAL;
+	}
+
+	/* Check for TRX-specific OML link first */
+	if (to_trx_oml) {
+		if (!sign_link->trx->oml_link)
+			return -ENODEV;
+		msg->dst = sign_link->trx->oml_link;
+	}
+	return abis_sendmsg(msg);
+}
+
 /* Send a OML NM Message from BSC to BTS */
 static int abis_nm_queue_msg(struct gsm_bts *bts, struct msgb *msg)
 {
@@ -480,7 +500,7 @@
 	return 0;
 }
 
-static void abis_nm_queue_send_next(struct gsm_bts *bts)
+void abis_nm_queue_send_next(struct gsm_bts *bts)
 {
 	int wait = 0;
 	struct msgb *msg;