This commit belongs to issue #4, allow to set the EqFct code in mapping file.
In VariableMapper a std::map with location(string) and code(int) was added.
With getLocationAndCode() this map is returned and used in eq_creat.cc to add missing locations with
10 default, or with 'code' set in the <location> tag in the mappinmg xml file.

Fixes #21

This closes #19

Added CMakeLists.txt + support files to allow building the project via cmake. The cmake files used by other project to find this library as a dependency still have to be added.