User interaction improvements

635fd6c Reading from stdin in JS wasn't working due to legacy code not being removed. (Not that anyone uses reading from stdin anyway).
d408f13 The print function in C takes multiple arguments and prints them out separated by a space. The JS version now does the same.
682b4e1 Added a prompt function that takes a string and returns a string. This allows implementation of basic programs such as COMP102 assignment 1:

    method printNameTag {
        def name = prompt "What is your name?"
        print "*********************************"
        print "*                               *"
        print "*  HELLO, my name is            *"
        print "*                               *"
        print "*          {name}               *"
        print "*                               *"
        print "*********************************"
        print
    }

    printNameTag

I expect that the way I've implemented d408f13 and 682b4e1 are not how you would have done it, so just let me know how I should change them, or if I should discard the changes completely.