test.py: Add support for repeated tests, print averages
ndstep stagiter: 10D -> 50D

Based on our benchmarks seems to result in better behavior, e.g. on b4
more persistence definitely pays off.
test.py: Add DimSelectHistory
test HistoryRA: New dimselect strategy - history + running average instead of total
test DimSelectWrapper: New class with meta-functionality
test dimselect: Add support for epsilon-greedy exploration, by default on
test -b BURNIN: Configurable, move from dimselect methods to the wrapper
test DimSelectHistory*: Fix multiple issues
test stagiter: Make configurable via -t
test: Add difficulty normalization to *diff, can be turned off via -N