[MOAB-dev] ***NOTE*** MBInterface::load_file API change

[Jason Kraftcheck]

In check-in r3343, I changed the signature of MBInterface::load_file in such
a way that it will break any existing code outside of MOAB that is calling
that function.

MOAB no longer creates an entity set for each file read operation.  Thus
load_file had to change because the previously required reference to an
MBEntityHandle via which that entity set was returned to the caller no
longer makes sense.  Instead, load_file accepts a "const MBEntityHandle*"
which may be, and defaults to, NULL.  To obtain the previous behavior of
having the contents of the file placed in an entity set, the caller must
*create* an entity set and pass in the address of the handle.

- jason