Added number-IO problem
Merge branch 'behavioral-diversity' into prog-synth-benchmarks

Conflicts:
	src/clojush/globals.clj
Made number IO problem able to print behavioral diversity
Changed printing of test errors to better identify failed test cases.
Started checksum problem file
Number-IO updated for input/output stack
Merge branch 'io-stacks' into io-stacks-prog-synth
Merge branch 'behavioral-diversity' into prog-synth-benchmarks
Merge branch 'behavioral-diversity' into prog-synth-benchmarks
Moved Levenshtein distance to util, and added median problem file
Changed problem atom-generators for number-IO and median to use new fn
Merge branch 'behavioral-diversity' into prog-synth-benchmarks
Finished median problem and fixed small typos in number-IO.clj
Changed max-error in median to 1
Merge branch 'master' into prog-synth-benchmarks
Fixed potential divide by zero error in IFS
Merge branch 'fix-IFS-div-by-zero' into prog-synth-benchmarks
Trying to cover more of the common cases that could be left out of random cases.
Trippled the number of Median training cases
Reduced median training cases back to 100.