The existing tests have been rewritten to take their test data from
local files instead of attempting to download them --- the urls were
broken.

The large file test has been deleted.

New tests have been added for:
  - the key-based indexing of channels, which is existing
  functionality
  - the key-based indexing of multiple channels, which is to be
  implemented
  - the integer indexing of individual samples, which is to be
  implemented
  - the collection of integer indexing of multiple samples, which is
  to be implemented

Multiple channels can be indexed using a Vector of Strings
Individual samples can be indexed using an Integer
Multiple samples can be indexed using a Vector of Integers

I realised I was just rewriting the implementation of AxisArray. This
commit introduces the tests for a new FlowSample struct which is a
simple wrapper for AxisArray with some params attached.

AxisArray performance is supposed to be good, the interface doesn't
have to change, and they can easily be converted to matrices as needed
by GigaSOM.

These changes add lots of indexing options for FlowSamples.

I have tried to keep backwards compatibility with the old FlowSample,
I think we have it, but cannot be absolutely certain.

…0-01-00-09-49-374-1964714061

CompatHelper: add new compat entry for "AxisArrays" at version "0.4"

The axes of the FlowSample data are now called :param and :event

size calls refactored to include dimension

version bumped

Base.axes redefined to call out to AxisArrays versions

Tests for large file added back in

Iterate just forwards the method to AxisArrays

A warning is emitted when the user tries to access params or data
directly.

Tests for these warnings are also added.

FCS TEXT segment keywords can now be accessed using the dot
syntax. E.g. `flowrun.par` retrieves the "\$PAR" keyword value.

Dot syntax access to `data` and `params` throws deprecation warnings.

`Base.propertynames` produces a list of the keywords for the
`FlowSample`.

This commit adds tests for these features also.