Add builtin functions for table operations

[darrylabbate]

• [ ] min()/max()
• [ ] sum()
• [ ] sort()
• [ ] select()
• [ ] push()/pop() (dequeue()?)
• [ ] pack()

[darrylabbate]

Note that whenever closures are implemented (#22), sort() should be refactored to take a user-defined function as an optional argument