fix CirculatorT type-pun warning on GCC6

fixes #28

See merge request !78

(fixes #28)

changed incorrect class into struct



See merge request !77

document that DecimaterT::decimate does not perform garbage collection on the mesh

addressing #27 

See merge request !76

Hash functions



See merge request !75

Vs2015 update3



See merge request !74

Split openmeshcore static/shared MinGW compilation

As with ms compilers, the shared/static compilation depends on export macros.

Besides this is inconsistent with the behavior for openmeshtools library.

Why did you add this ?

See merge request !72

As with ms compilers, the shared/static compilation depends on export macros.
Anyway this is inconsistent with the behavior for openmeshtools library.

Why did you add this ?

- Based on the macro provide partial specializations for std::hash<>
- for vertex,halfede,edge, and face handles.
- Add a free function hash_value(BaseHandle) for boost::unordered_set/map

Mingw changes

TODO: Test 

See merge request !68

(cherry picked from commit ec84b475)

(cherry picked from commit a564a30c)

Handle nr newlines



See merge request !71

Throw error when no readers are available



See merge request !69

Convert 2 unix



See merge request !70