HOWTO generate random numbers

[hobovsky]

Create a description of how to generate random numbers in languages with limited functionalities.

For example, C has only rand, which is able to generate int in limited range. It could be useful how to generate large random numbers, numbers in range, streams of numbers, floating point numbers, etc.

Decide if the better way is to create some language-agnostic description of methods, or a set of language-specific snippets.