- figure out how Pd-extended is going to load this stuff in order to maintain
  maximum capatibility

- replace pd-extended's x_gui.c with this e_gfxstub.c

- replace pd-extended's d_math.c with this e_sqrt.c

- move this d_math.h to pd-extended's pd/src

- move relevant help patches from pd-extended's pd/doc/5.reference to here

- move relevent help patches from doc/pddp to here