This version is incompatible with previous versions
of MIDAS due to some (minor) renaming of modules.

More complete doctests and examples.

Changes required for existing scripts:

   * instead of using "import midas" USE "import midas.rectgrid"
     for logically rectangular grids.
   * the "rectgrid" class has been renamed "quadmesh"
   * if you are using the  profile module, "import midas.profiles"
   * "grid_overlay" has been renamed "subtile"