String formatting

[gustavwilliam]

Formatting strings is an important part of any language. Here's one possible way to do it

>>> "Gustav" :name var
>>> "Hello {0}!" {name}] format println
"Hello Gustav!"

This would use linked lists to store the values to replace the placeholders in the string with. Just like in python, we could include some interesting options for the formatting (by changing what is inside the {} in the string).