fix possible division by zero in ccdemos/common_ply.h don't use DEFS variable in makefiles, just add it to CCFLAGS compile float version of libs with -fsingle-precision-constant

Makefile: added help and distclean target, plus small fixes ccdemos/common_sdl.h: print fps to window caption instead of console update and key callbacks fixed segfault when resizing window pressing c now causes print out of camera coordinates ccdemos/spheres_shadow.cc: controlling position of a light and focal length of camera

ccdemos: put the common code to header files, common_ply.h and common_sdl.h move all ccdemos on octree and make them all realtime (-i argument)

realtime_dragon demo: now fullsize model + octree realtime_bunny demo: bigger resolution Box, Sphere: implemented AABB intersection new stop condition for octree building (when number of shapes in children >= 6x shapes in parent node) fixes for octree traversal

octree traversal rewritten to avoid recursion reenabled -O3 optimizations (was accidentaly disabled, now it traces even faster! :-)) realtime_bunny: added FPS counter, fixed a bug in ply loader min3 and max3 templates added to common.h

new virtual Shape::intersect_bbox implementation of triangle-AABB intersection octree building updated and simplified with help of this new method octree made default for Python, it's currently much faster than kd-tree (both building and traversal)

new space partitioning structure: octree realtime_bunny updated to use octree plus other files updated to be container type independent (only user programs are supposed to include and use special containers)