test_storage: extend test harness; datastorage: two bug fixes

datastorage (bug fix): deleting expired array item would fail to test next item
test_storage: extended to cover all required datastorage entry points
test_storage: added ability to read script file
test_storage: added new and revised test scripts
TESTING.md: added to describe testing approach
general: added various TODO notes on things to come back to
general: revised #includes to make each "self-compiling"
general: revised #includes to minimise usage across source files
general: moved declarations and defintions to simplify and rationalise code
datastorage: refactor to support scalability testing
datastorage: made independent of time() calls to support testing
datastorage: fixed redundant use of both SORT_NUM and SORT_LENGTH defines
datastorage: fake kicking to test clients move between access points
msghandler: new module to reduce compile time interdependencies
mshhandler: (issue #100?) fixed SEGV memcpy() in dump_client() using strncpy()
ubus: merged uface into ubus
mac_utils: new module for MAC address utilites
test_header: added target to help #include rationalisation

Tested-by: Nick Hainke <vincent@systemli.org>

src/test/simple_kick.script

@@ -0,0 +1,5 @@
+dawn min_kick_count=2
+ap bssid=11:22:33:44:55:66
+client bssid=11:22:33:44:55:66 client=ff:ee:dd:cc:bb:aa
+kick 11:22:33:44:55:66 0
+kick 11:22:33:44:55:66 0