Arduino Tests & Error Corrections

[pschatzmann]

Unit Tests

• I added the functionality for unit tests in Arduino in examples/TestsArduino: For this I made all the methods in test.h static to prevent linker errors. Maybe a cleaner solution would have been to split things up into a proper test.c and use the test.h only for the method declarations.
• The tests have extended to cover the handling of uninitialized memory by replacing tsd_context_init with a custom test_context_init. By default this is deactivated!
• The tests have been extended to cover the execution of the callbacks in [set_event_callback.c] to cover and demonstrate callback not called on ESP32 microcontroller #10

It includes 2 corrections to tsdemux.c taddressing #10

• calling calloc instread of malloc
• calling ctx->free instead of free