Add T4 bit map compression routines

Add bit map encoder and decoder functions: decoder is fully functional
while encoder is good enough for testing - no backtracking to find
the best possible compression is implemented. If somebody is willing to
implement MS side of EDGE than this has to be expanded.
Add corresponding tests.
N. B: the encoding is implemented according to ETSI TS 44.060 which is
slightly different from T4 used for fax according to CCITT G31D (RFC 804).

Ticket: OW#2407
Sponsored-by: On-Waves ehf

Signed-off-by: Max <msuraev@sysmocom.de>
diff --git a/tests/testsuite.at b/tests/testsuite.at
index 9cda1de..3d4d526 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -27,6 +27,12 @@
 AT_CHECK([$abs_top_builddir/tests/bitvec/bitvec_test], [0], [expout], [ignore])
 AT_CLEANUP
 
+AT_SETUP([bitcomp])
+AT_KEYWORDS([bitcomp])
+cat $abs_srcdir/bits/bitcomp_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/bits/bitcomp_test], [0], [expout])
+AT_CLEANUP
+
 AT_SETUP([conv])
 AT_KEYWORDS([conv])
 cat $abs_srcdir/conv/conv_test.ok > expout