Partial transition to Elixir 0.13.3
more syntax changes
a few more updates
Fix forth exercise
Fix#	rna-transcription/results
Merge remote-tracking branch 'origin/elixir-0.13.3'

Conflicts:
	etl/etl_test.exs
	forth/example.exs
	grade-school/grade_school_test.exs
	nucleotide-count/nucleotide_count_test.exs
	palindrome-products/palindrome_products_test.exs
	parallel-letter-frequency/example.exs
	pythagorean-triplet/pythagorean_triplet_test.exs
	word-count/example.exs