UPD, ENH: improve RNG

[vkhodygo]

These are all the features that need to be implemented at some point:

1. int
   • Streams
     • Streams
     • Streams from 0 to some n (n not included by default)
     • Streams from some m to some n (m is included and n is not by default)
     • Streams from 0 to some n with a boolean flag that allows n to be included; the default value is false
     • Streams from some m to some n with a boolean flag that allows n to be included; the default value is false
     • Streams of a given size
     • Streams of a given size from 0 to some n
     • Streams of a given size from some m to some n
     • Streams of a given size from 0 to some n with a boolean flag
     • Streams of a given size from some m to some n with a boolean flag
   • Singular values
     • Values from 0 to some n (n not included by default)
     • Values from some m to some n (m is included and n is not by default)
     • Values from 0 to some n with a boolean flag that allows n to be included; the default value is false
     • Values from some m to some n with a boolean flag that allows n to be included; the default value is false
2. long
   • Streams
     • Streams
     • Streams from 0 to some n (n not included by default)
     • Streams from some m to some n (m is included and n is not by default)
     • Streams from 0 to some n with a boolean flag that allows n to be included; the default value is false
     • Streams from some m to some n with a boolean flag that allows n to be included; the default value is false
     • Streams of a given size
     • Streams of a given size from 0 to some n
     • Streams of a given size from some m to some n
     • Streams of a given size from 0 to some n with a boolean flag
     • Streams of a given size from some m to some n with a boolean flag
   • Singular values
     • Values from 0 to some n (n not included by default)
     • Values from some m to some n (m is included and n is not by default)
     • Values from 0 to some n with a boolean flag that allows n to be included; the default value is false
     • Values from some m to some n with a boolean flag that allows n to be included; the default value is false
3. double
   • Singular values
     • Default generator for numbers in [0, 1)
     • Generator with a flag that allows 4 different unit ranges: [0, 1), [0, 1], (0, 1], (0, 1)
     • Default generator for [0, bound) 5a89fdf
     • Default generator for different ranges for the pair 0, bound 5a89fdf
     • Default generator for a custom range 5a89fdf
     • Default generator for different types of an interval 5a89fdf
   • Streams
     • Default stream
     • Default stream of size n
     • Stream for different unit ranges
     • Stream of size n for different unit ranges
     • Stream for a custom range that's a semi-open interval [a, b)
     • Stream for a custom range that's one of the four possible interval types: [a, b), [a, b], (a, b], (a, b)
     • Stream of size n for a custom range
     • Stream of size n for a custom range that's one of the four possible interval types
4. float
   • Singular values
     • Default generator for numbers in [0, 1)
     • Generator with a flag that allows 4 different unit ranges: [0, 1), [0, 1], (0, 1], (0, 1)
     • Default generator for [0, bound)
     • Default generator for different ranges for the pair 0, bound
     • Default generator for a custom range
     • Default generator for different types of an interval
   • Buffer
     • Add a buffer to generate two float numbers from one long.
5. Gaussian & exponential
   • New implementation if needed
6. Improved MT
   • Parallel/faster implementation