Removed libslic3r from the default include paths for all modules but libslic3r. Now headers from libslic3r need to be included with an explicit path (libslic3r/libslic3r.h etc) Split the localization macros into I18N.{cpp,h}
+ corrected Sidebar layouts + deleted get_preset_bundle + actions with tabs_list moved to GUI_App
The XS was left only for the unit / integration tests, and it links libslic3r only. No wxWidgets are allowed to be used from Perl starting from now.