[lib] CLUnfolder.__msolve_constraints and MCLAnalyser.__mac_exhaustive_search now return tuples => Creation is more efficient

[lib] Improve RawSolution.extract_act_input_clock_seq(): processing of solutions is ~15% more efficient

[lib] Try to improve the autogenerated code by reducing the number of nested try/except/finally blocks

- tests/testPID3 is model name that is not supported; if the reporter status is not checked we can't know if an error occured...

test_type_error1: was generating an error wrongly,
test_type_error2: Clarification on what the test is supposed to get
(deliberately generates an error)

- Adapt search files from unittest to pytest
- Examples files for tests are now packaged with the module

These solutions are much more accurate and don't trigger useless clocks in the steps of the solutions

- Allow optimal comparisons between solutions and steps
- /!\ Sets are used so the order of clocks and events are not tested anymore /!\

=> Not supported anymore since it is a private attribute of the C++ class
This feature is only used during tests so, not very important (?)

- Fix temp dirs
- Fix test_frontier for model4
- Use future print_function
- Add doc when possible