Initial work for a GUI for the cut feature
First working implementation of a GUI for cutting
New option for rotating the lower part resulting from the cut so that the flat surface lies on the print bed
Use a slider for the cutting GUI
Fix islands not being ordered efficiently with the logic that completes each of them before moving to the next one (which is now the default behavior). #1137
Update MANIFEST. #1969
Fix regression causing default extrusion width to be ignored. #1958
Bump version number
Update the [timestamp] placeholder(s) at every G-code export. #1957
Removed debugging line left
One more fix after recent fix to default extrusion width
Explain that infill_every_layers can be set to arbitrarily large values in the tooltip
Exclude support from bridged areas
More correct test description
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&.
Merge branch 'master' of git://github.com/alexrj/slic3r into feature-xs-types