Fix the tween calculation for the inbetween frames. Now, we can use primitive instead og group to defin ethe animation. Currently, it has been tested against rectangle only. We need to check others as well.

SUBDIRS = src include tools examples inkscape
pkgconfigdir = $(libdir)/pkgconfig
pkgconfig_DATA = libmbfly.pc
EXTRA_DIST = libmbfly.pc.in Doxyfile README.h

if NODEJS
  SUBDIRS += nodejs
endif