* Break classes_body_item.cpp(.h) into more reasonable size bites.
* Rename classes_body_item.cpp(.h) to lib_draw_item.cpp(.h)
* Fix some unsatisfied header file dependencies.
* Add stubs to component library draw item base classe to handle editing
  internally.
* Lots of code cleaning.

in bezier_curves: changed  calculations like dx*dx to (double)dx * dx to avoid integer overflow in calculation