re-structure the OpenBSC directory layout

The new structure divides the code into a number of libraries
for the BSC core functionality, MSC core functionality, Abis transport,
TRAU and other bits.

This doesn't introduce any functional code change but simply moves
around files and alters Makefile.am accordingly.

Next step would be to disentangle a lot of the inter-library
dependencies and make the individual bits of code more independent.
diff --git a/openbsc/.gitignore b/openbsc/.gitignore
index f9dacac..bd35256 100644
--- a/openbsc/.gitignore
+++ b/openbsc/.gitignore
@@ -6,10 +6,9 @@
 bscconfig.h
 bscconfig.h.in
 openbsc.pc
-bsc_hack
-bsc_msc_ip
+src/osmo-nitb/osmo-nitb
 bsc_mgcp
-src/bsc/osmo-bsc
+src/osmo-bsc/osmo-bsc
 *.*~
 *.sw?
 
@@ -31,15 +30,15 @@
 
 # apps and app data
 hlr.sqlite3
-bs11_config
-ipaccess-config
-ipaccess-find
-ipaccess-firmware
-ipaccess-proxy
-isdnsync
-bsc_nat
-osmo-sgsn
-osmo-gbproxy
+src/utils/bs11_config
+src/ipaccess/ipaccess-config
+src/ipaccess/ipaccess-find
+src/ipaccess/ipaccess-firmware
+src/ipaccess/ipaccess-proxy
+src/utils/isdnsync
+src/nat/bsc_nat
+src/gprs/osmo-sgsn
+src/gprs/osmo-gbproxy
 
 #tests
 tests/channel/channel_test