Add Random class with seed support.

[iliabylich]

Modified random-based core methods to use Random:

opal-repl
>> srand(10); 1.upto(10).to_a.shuffle
=> [4, 1, 2, 3, 7, 8, 6, 5, 9, 10]
>> srand(10); 1.upto(10).to_a.shuffle
=> [4, 1, 2, 3, 7, 8, 6, 5, 9, 10]
>> srand(20); 1.upto(10).to_a.shuffle
=> [1, 6, 8, 5, 7, 4, 10, 2, 3, 9]
>> srand(20); 1.upto(10).to_a.shuffle
=> [1, 6, 8, 5, 7, 4, 10, 2, 3, 9]

[elia]

@iliabylich 👍🏼 to merge, you had a look to #657 also?

[iliabylich]

@elia Yeah, I've extracted some code from those PR 😄 But it was easier to rewrite everything (since it's outdated) and use some simple random generator.