Note: The real bug tracking happenes in the bugs/ directory.
      We use the ditz program for this purpose.

 * Interface
   Change global_last_quad_index to global_quadrant_offset
   Remove the p4est quadrant_pool member
   Let the refine and coarsen callbacks see the originating quadrant(s)
 * Mesh generation
   2D interface to pfudg
   Verify trilinear mesh extraction
 * Helper functions / algorithms
   Verify p4est_quadrant_is_inside_tree function
   Isolate a p4est_tree_is_valid function
 * Balance
   Make edge/face only balance optimal and configurable
   Deal with p4est counters modified by balance_subtree
   Check the inter-tree face-only/edge-only local balance
 * vtk output
   geometry in 2D
 * Optimization
   Speed up p4est_quadrant_compare
   Speed up p4est_intxx_t_compare
 * Include a test case for every major functionality
 * Documentation using doxygen
 * Make the roots of the forest distributed in parallel
