License file added
switch block: deviation check removed, unit test implemented
methods for logging std::ostream and unsigned int added

(cherry picked from commit d45705781fa5da041194a187c057bc86232d6721)
debug outputs added to periodic thread class
a matrix object can now be shifted into a std::ostream
switch block: getter added for current input
saturation block implemented
unit tests for class matrix enhanced
gain block improved, unit tests added
matrix class: made getNofRows() and getNofColums() constexpr
matrix class: bug fixed and template parameter types changed.

- recursive template instantiation for types with M < 1 and N < 1 prevented
- template parameter types (for M and N) changed from uint8_t to unsigned int
matrix class: method added for getting a sub matrix
handling of system time improved, unit tests added (code for windows is untested)
made Signal class compatible to std::array and conform matrix class to std::array by adding a size() method
saturation block can now be used with fix sized containers like eeros::math::Matrix or std::array
Merge remote-tracking branch 'mzueger/develop' into flink