Minor tweaks and changes

[JamieHeather]

• Add ability to input own indexes to demultiplexing script
• Add ability to input own spacer sequences to collapsing script
• All scripts should output their version number to the log file
• The argparse intro line should take version number from version variable
• Each script should have a --version/-v argparse option, fed off version
• In Decombinator, the AmbiguousBaseCall(Barcode) filter is more properly named just a count - perhaps add an additional layer of optional filtering here?