#103 Importing biases from aedat

[Sim Bamford]

Import biases / preferences from aedat file. Optional? Default? Not sure what the right behaviour should be.

[Tobi Delbruck]

Requires developing a filter for the input stream that reads the aedat file to strip out the comment headers and the pre-xml header and to terminate the stream at end of the xml. Not a big job but a headache. Needs implementing in two places, the BiasgenFrame and FilterFrame