Draft: feat: updated NormalDistribution, Alphabet, Range, Cutter classes. Add Picker class.

1. NormalDistribution: changed rounding behaviour in randomInt() method to prevent observed biases when using range with length 1. Example: (0,1)
2. Alphabet: add plus and minus sign, bool values support.
3. Markup and Tape classes, due their identical logic, merged into a single class - Picker.
4. Picker: add support for a zero-length range to the _countRightBoundIndex() method.
5. Cutter: add generation array with NULL values support.
6. Range: changed checks is constructor to support zero-length range. Example: (1,1)
7. Mocks: removed MarkupMock, TapeMock and add PickerMock class.
8. Add NULL support for String, UnsignedInt, SignedInt, Bool types.
9. Add jsdocs for classes and other minor typo refactoring.

Closes #2 (closed)