0.7.2

• Improved performance of Regex
• Fixed lexing of octal characters and strings (thanks @rhysd)
• Time.parse can return UTC times (thanks @will)
• Handle dashes in crystal init (thanks @niftyn8)
• Generic type varaibles can now only be single letters (T, U, A, B, etc.)
• Support %x and %X in sprintf (thanks @yyyc514)
• Optimized Int#to_s (thanks @yyyc514)
• Added upcase option to Int#to_s, and use downcase by default.
• Improved String#to_i and fixed the many variants (to_i8, to_u64, etc.)
• Added Time.at (thanks @jeromegn)
• Added Int#upto, Int#downto, Int#to iterators.
• Added Iterator#cons and Enumerable#each_cons (thanks @porras)
• Added Iterator.of, Iterator#chain and Iterator#tap.
• Allow top-level private macro (similar to top-level private def)
• Optimized BufferedIO writing performance and memory usage.
• Added Channel#close, Channel#closed?, Channel#receive? and allow them to send/receive nil values (thanks @datanoise).
• Fixed Process#run after introducing non-blocking IO (thanks @will)
• Tuple#map now returns a Tuple (previously it returned an Array)
• Tuple#class now returns a proper Class (previously it returned a Tuple of classes)
• Lots of bug fixes.