Reference output files for examples

[lplana]

It is possible to test implementation correctness by comparing the output files generated by the examples in the repository with reference output files.

The reference files are attached here. Please note that the extension has been changed from '.out' to '.txt' due to repository file type restrictions.

example rand10x40:
REF_rand10x40_test_20e.txt
REF_rand10x40_train.txt
REF_rand10x40_train_test_20e.txt

example rogers-basic:
REF_rogers-all-links.txt

example simple_past_tense:
REF_simple_past_tense_train_test.txt

[Christian-B]

These files can easily be read in using numpy.loadtxt.

If you create test just commit the expected results along with the tests.
We used that approach in
https://github.com/SpiNNakerManchester/sPyNNaker/tree/master/spynnaker_integration_tests/test_param_vertex