add a module init file
sensible init
gitignore
parallelised quiver plots with shared progress bar

- limit useful data range
  For a given run, only a subrange of the frames actually contains
  anything useful. Add an argument to the instantiation of a Run that
  allows us to specify this range.

- remove matplotlib animation (not really suitable for lots of images)

- explicitly create and terminate processes
  Stopped using mp.Pool as it was eating lots of memory. Now just create
  a load of individual Process in batches and throw them at the
  processors :). Dealt with the memory issue. Now have a Queue to store
  data as it is created.

- Shared progressbar based on BaseManager from multiprocessing.
  Now with a single parallel processing function that returns a result if
  desired. This result is not ordered, but that doesn't matter as we can
  order based on properties of the returned objects anyway (always
  frames).

- Tests and example test data for frame and run.

- Reorganise, separate out some util functions