Initial import memory manager
Merge remote-tracking branch 'remotes/local_v/memory_manager'
* changed pico_free into PICO_FREE
* changed pico_zalloc into PICO_ZALLOC
Added 2 missing architecture files (pico_avr.h and pico_str9.h)
Added two new architectures in the Makefile:
    * AVR
    * STR9
A remote ZMQ server can now receive data sent via a REQ socket
commit before stash
Commit before merge with mem manager ( used for better mocking of pico_zalloc )
- Solved problem with mocking pico_zalloc. We merged with the futured memory manager and now compile our tests with
  the memory manager flag on. This allows to easily mock PICO_ZALLOC.
- Refactored ZMQ tests so they use the mocked version of pico_vector and PICO_ZALLOC
- Merge branch 'master' of /home/sam/Documenten/FinalMem/picotcp into zmqdev

Conflicts:
	Makefile
	modules/pico_zmq.c
	stack/pico_device.c
	test/units.c
Merge branch 'zmqdev' of https://github.com/tass-belgium/picotcp into zmqdev

Conflicts:
	modules/pico_arp.c
	modules/pico_zmtp.c
	stack/pico_socket.c
	test/unity_tests/Makefile
	test/unity_tests/Testzmq_tests.c
	test/unity_tests/Testzmq_tests_Runner.c
	test/unity_tests/Testzmtp_tests.c
	test/unity_tests/Testzmtp_tests_Runner.c