Move src/*.{c,h} to src/core/

This way we have all libosmocore.so in an own subdir instead of having
lots of files in the parent dir, which also contains subdirs to other
libraries.
This also matches the schema under include/osmocom/.

Change-Id: I6c76fafebdd5e961aed88bbecd2c16bc69d580e2
diff --git a/debian/copyright b/debian/copyright
index 79c5876..31a2946 100644
--- a/debian/copyright
+++ b/debian/copyright
@@ -13,23 +13,23 @@
 
 Files: include/osmocom/core/loggingrb.h
        include/osmocom/core/strrb.h
-       src/strrb.c
-       src/loggingrb.c
+       src/core/strrb.c
+       src/core/loggingrb.c
 Copyright: 2012-2013 Katerina Barone-Adesi <kat.obsc@gmail.com>
 License: GPL-2+
 
 Files: include/osmocom/core/linuxrbtree.h
-       src/rbtree.c
+       src/core/rbtree.c
 Copyright: 1999 Andrea Arcangeli <andrea@suse.de>
            2002 David Woodhouse <dwmw2@infradead.org>
 License: GPL-2+
 
 Files: include/osmocom/core/crc16.h
-       src/crc16.c
+       src/core/crc16.c
 Copyright: 2005 Ben Gardner <bgardner@wabtec.com>
 License: GPL-2
 
-Files: src/utils.c
+Files: src/core/utils.c
 Copyright: 2011 Harald Welte <laforge@gnumonks.org>
            2011 Sylvain Munaut <tnt@246tNt.com>
            2014 Nils O. Selåsdal <noselasd@fiane.dyndns.org>
@@ -100,8 +100,8 @@
 License: GPL-2+
 
 Files: include/osmocom/core/stats.h
-       src/stat_item.c
-       src/stats.c
+       src/core/stat_item.c
+       src/core/stats.c
        src/vty/stats_vty.c
        tests/stats/stats_test.c
 Copyright: 2009-2010 by Harald Welte <laforge@gnumonks.org>