Some initial work for implementing wireframe
Refactoring: moved some low-level G-code generation methods to the new Slic3r::GCode::Base class
Refactoring: moved the ooze prevention logic into a separate class with hooks
Adapt wireframe.pl to the new GCode interface
Moved Slic3r::GCode::Base to its own file
Refactoring: moved most of the low-level G-code to the Slic3r::GCode::Base class. Cleanup of the retraction and wipe logic.
Remove wireframe.pl from the gcode-refactoring branch so that we can merge it into master
Merge branch 'gcode-refactoring'