vchoi_fork

[svn-r343] First implementation of collective access support.

H5D.c
    Changed H5D_write and H5D_read to recognize collective transfer
    requests.  Current algorithm puts the xfer-mode in the file->mpio
    structure.  Not thread safe.  Need to revise it to pass transfer
    parameter as a function parameters to the lower levels.

H5Dprivate.h
H5Dpublic.h
    Added xfer_mode to the transfer property list structure.
    Added defination of transfer modes, H5D_XFER_INDEPENDENT and
    H5D_XFER_COLLECTIVE.

H5Farray.c
    Added code to handle collective access requests.  Currently
    works for one contiguous block at a time.  Need to revise
    it with the MPIO low level calls to combine all blocks as
    one truely collective call.

H5P.c
H5Ppublic.h
    Added H5Pset_xfer and H5Pget_xfer routines that can set and get
    the transfer mode of a data transfer property list.