Script for .mrc file which splits channels

[hailstonem]

Also takes cmd-line arguments
Note use of getPlanes over getPlane for efficiency.

[carandraug]

1. edit omero2mrc.py instead of copying the file and modifying it.

2. instead of modifying write_imsubs to create each image file, have a function that will write the file given an image that only has that channel. Note that currently, while you are writing files with only one channel, the metadata is still mentioning all the other channels.

3. make the split of channels an option.

4. remove the print commands. At the very least, make then conditional when running in debug mode.

5. make individual commits for each thing you change. 1 commit to add the parsing of options, another command to add the splitting of channels.