Promise based release

• Added example 5 - Traveling salesman problem 7334185
• Added example 4 - string combination optimization 4858349
• Updated example 3 73f9c86
• Updated example 2 3e3424d
• Updated example 1 d31d9c9
• Benchmark empty run now returns info by default 7a72ccd
• Using object destructurig 5187d3d
• Replaced callbacks with Promises bed78a7
• Returning self after configuration to stack calls 1cfc6bc
• Added fitness target tolerance f4257c8
• Removed fitness timeout option 4658538
• Added support to train strings and combinations a1804eb
• Replaced 'let' with 'const' in various places 0d7b1f8
• Added advanced array manipulation helper functions 3af49b4
• Added async and promise helper functions e6e66e5
• Added isString 5050f02

v1.1.2...v2.0.0