Closes #35

Apply suggestion to src/Helpers/TimeAndDate.cpp

Update documentation for the ECSS definitions

Group Services and ECSS Definitions into a doxygen page

This marks completion of the arbitrary type field feature

Suggested by @xlxs4

Other changes:
Tweaked addNewParameter() in order for the IDs to be arbitrary (insertion
of already existing ID test incoming) according to suggestion by @kongr45gpen

Suggested by @xlxs41

Cause was an off-by-1 error in construction of the Parameter objects.
Minor changes to documentation

Also update some of the tests

Also update some of the tests

Need to fix linker errors. Also updated documentation.

As suggested by clang-tidy

in order to make construction and adding more natural

Keep consistent the declaration of the execute functions in all child classes and change the scope of the execute function in the MemoryManagementService