Use Bitshuffle instead of hdf5plugin

[noemifrisina]

Bitshuffle is generally faster than hdf5plugin for data compression.

When trying to copy and compress mask and flatfield for Tristan, there was an issue with Bishuffle that caused an Illegal instruction (core dumped) error when running code blocks like the following:

flatfield=h5py.File(flatfieldfile, "r")["image"]
bitshuffle.h5.create_bitshuffle_compressed_dataset(nxdetector, b"flatfield", shape=flatfield.shape, dtype=flatfield.dtype, chunks=(100, flatfield.shape[1]))
nxdetector["flatfield"][:] = flatfield[()] 

block_size=0
flatfield=h5py.File(flatfieldfile, "r")["image"]
nxdetector.create_dataset("flatfield", data=flatfield[()], chunks=(100, flatfield.shape[1]), compression=bitshuffle.h5.H5FILTER, compression_opts=(block_size, bitshuffle.h5.H5_COMPRESS_LZ4))

For now nexgen is using hdf5plugin.