Solutions for the dart exercism track

Exercises taken from https://exercism.io/ or https://github.com/exercism/dart.

Also a chance to try out test && commit || revert as explained by Kent Beck.

Core exercises

#.	Title	Done
1	Hello World	✓
2	Two Fer	✓
3	Leap	✓
4	Scrabble Score	✓
5	Armstrong Numbers	✓
6	Difference Of Squares	✓
7	Word Count	✓
8	Bob	✓
9	Space Age	✓
10	Hamming	✓
11	Gigasecond	✓
12	Raindrops	✓
13	RNA Transcription	✓
14	Anagram	✓
15	Pascal's Triangle	✓
16	ISBN Verifier	✓
17	Binary Search Tree	✓

Side exercises

#.	Title	Done
1	Diamond	✓
2	Matching Brackets	✓
3	Resistor Color	✓
4	Resistor Color Duo	✓
5	Reverse String	✓
6	Isogram	✓
7	Acronym	✓
8	Phone Number	✓
9	Prime Factors	✓
10	Darts	✓
11	Pangram	✓
12	Luhn	✓
13	Minesweeper	✓
14	Collatz Conjecture	✓
15	Nth Prime	✓
16	Allergies	✓
17	Triangle	✓
18	Secret Handshake	✓