New --cut feature
Finished --cut implementation
Fix cut() test
Merge branch 'master' of git://github.com/alexrj/slic3r into feature-xs-types
Updated xs type hangling

Type handling is mainly done using templates.

Template Slic3r::ClassTraits is used to store info about exported types (perl class name).

Template values are initialized by REGISTER_CLASS macro, it is used in .cpp files.

Ref<type> class is used to return value as perl reference. Operator overloading is used to make c++ and XSpp happy, only pointer
value should be possible

Clone<type> class is used to return copy of value ( using new and copy constructor). Copy is created on assigment,
this should be probably improved (memory lead on multiple assignments).
It is overloaded to be able to return type, type* and type&.