Various fixes and features

c9499fe Reading from stdin in JS wasn't working due to legacy code not being removed. (Not that anyone uses reading from stdin anyway).
95fb841 The print function in C takes multiple arguments and prints them out separated by a space. The JS version now does the same. Did I implement this in a good way?
9044e38 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

For 9044e38, `prompt` is now implemented in StandardPrelude (is it ok to import io in StandardPrelude?), and in order for that to work I had to add stdin.getline to gracelib.js. I also have a `Grace_prompt` method in gracelib.js that makes use of the JavaScript `prompt` function but I'm not sure how to override the one from StandardPrelude.

496fcf7 Compiler had "grace" target twice. Not really important.
9f41e82 Compiler wasn't checking for option arguments so would crash with a RuntimeError due to an invalid array index.
2286d79 Stops "0x" and "8x" etc. being valid numbers by requiring a number after the "x". The error message does leave something to be desired though.
bd39ef5 I noticed that the compiler actually had processed-ast as a target (AST after identifier resolution) so I added it to the JS UI. This could be useful for debugging, maybe for inheritance.
4f575de Stops wildcard identifiers showing up as __0 etc. in identifier resolution error messages. This does not prevent incorrect/undefined use of these variables though.
8a7d899 Removes trailing whitespace. I think I was asked to remove some in an earlier commit so thought I'd remove that which I did find.
c829c6b Allows indexed lists on the left side of binds. Turns out I was too restrictive in 9a3e0a8, only allowing identifiers and members.
10c4f51 Added a test to check list assignment and other list operations. To do this, I had to modify the JS version of asString for lists so that there is no spaces after commas when a list is printed as this is how it is in the C version. Generally for this and for other collections, is it preferred to have the space after the comma or not?