WIP Refactoring of exceptions:

1) All slicer's exceptions are now derived from Slic3r::Exception.
2) New exceptions are defined for slicing errors.
3) Exceptions are propagated to the Plater to show.
It remains to modify the slicing back-end to throw the new SlicingError
exceptions instead of std::runtime_error and to show the other exceptions
by a message dialog instead of a notification.

src/slic3r/GUI/ConfigWizard.cpp

@@ -123,7 +123,7 @@ Bundle& BundleMap::prusa_bundle()
 {
     auto it = find(PresetBundle::PRUSA_BUNDLE);
     if (it == end()) {
-        throw std::runtime_error("ConfigWizard: Internal error in BundleMap: PRUSA_BUNDLE not loaded");
+        throw Slic3r::RuntimeError("ConfigWizard: Internal error in BundleMap: PRUSA_BUNDLE not loaded");
     }
 
     return it->second;