The DAP code compiles constraints into an internal
tree form. When it goes to fetch data, it converts
that tree form into a string suitable for use in a url.
The tree->string code was using '<' when it should be
using '<=' and vice versa.
The fix is to make sure the right operator is used.
revisions are simpler, and I hope, clearer than the all
previous versions. Part of the code taken from the
ucar.nc2.Range.compose function. Modified to handle edge
cases not handled in the Range.compose function.
