CanBusToolbox

This adds some improvements to the library:

– Proper visibility attributrs for all symbols
– Defaulting standard functions whereever possible
– Code cleanup
– Bugfixes
– Fixing typos in the documentation
– Initialize internal structures properly
– Mark derived virtual Methods as “override”
– Free memory allocated by LinuxCanBusFinder also in case of an error
– Put all classes of the library into a namespace
– Use Doxygen's built-in STL support
– Raise C++ standard to C++17
– Add Library Prefix to Include Guards