Added faulty memory manager for unit tests
Added unit test cases for frame allocations using faulty mm
Fixed a NULL pointer dereference in ping
Finished coverage of pico_frame module
Increase coverage of pico_protocol module
Allow test compilation with the same obj as units for coverage tests
Wake up correctly from Zero-window when endpoint is Linux, due to Linux zero-window probe detection.

Fixed #107
Reverted erroneous fix in http_server
Moved ifdef to fix linker bug in mbed online compiler (because it uses pico_config to specify modules)
Refactored "process-in" from ipv4
Added memory statistics to tests
Removed code std violations from ipv4.c
Changed signs of all scheduler variables in pico_stack.c
Fixed misusage of tree in soecket setsockopt
Fixed yet another misuse of tree in setsockopt
Fixed a third tree misuse in the setsockopt
Reverted sign changes in the scheduler to avoid altering devices api
Removed last unsafe foreach from multicast setsockopt
Modified documentation for socket_read
Added check for null key in pico_tree_delete