Global.fromBigEndianBytes method

[aslesarenko]

A new Global.fromBigEndianBytes[TNum] method should be implemented which can parse big-endian two's complement binary representation of TNum type.

The type TNum can be one of Byte, Short, Int, Long, BigInt.

Examples:

val shortBytes = Coll(0.toByte, 16.toBytes) 
val s = fromBigEndianBytes[Short](shortBytes) // using global pre-defined function
// assert (s == 16.toShort)

val intBytes = Coll(0.toByte, 0.toByte) ++ shortBytes
val i = Global.fromBigEndianBytes[Int](intBytes) // using method of Global
// assert (i == 16)

It should be mutually inverse to Numeric.toBigEndianBytes, so that, continuing the above example:

val isEqual = i.toBigEndianBytes == intBytes
// assert (isEqual)

Related to toBigEndianBytes in #486