Add example directory with testing C code

[grzanka]

Sample C code, not necessarily from libamtrack. Code should contain proper doxygen and be structured in header and source files.

Ideally it should cover all cases:

• only in parameters
• only out parameters
• mixed in, out, in/out
• multiple out parameters
• mutplitle out parameters with different multiplicites
• functions with no parameters

[grzanka]

Add test to Github integration which checks if example code compiles under Linux (gcc) and Windows (visual studio), using CMake