[subscriber] Log changes in the usage of a subscriber (Andreas Eversberg)

Log changes of the use count of a gsm_subscriber.
tree: 04dfc5b2642c9c44258c95c8076e9bf511c0ccc9
  1. doc/
  2. tests/
  3. tools/
  4. AUTHORS
  5. configure.in
  6. COPYING
  7. Makefile.am
  8. README