Feature/unitest run all

[kam193]

This is a draft of possible simplifications for writing unit tests.

RUN_ALL macro runs all tests.

The unit test is registered during declaration of UNIT_TEST by special macro _UNIT_TEST_INITIALIZER which use __attribute__((constructor)) mark to run registration before running main.

Limitations:

• It's possible it will not work with some compilators (e.g. clang require something others), but I found that generally __attribute__((constructor)) should be available (this is gcc extension). But anyway, this is for simplify UT creations, not for general development
• Size for list of tests must be declared statically (but it is a problem to overallocate memory for test?)

Other possible improvements:

• don't use UNIT_TEST_REGISTER, merge it with UNIT_TEST