Ability to create multiline blocks in boa shell

[HalidOdat]

Instead of passing everything in one line.

function hello() {console.log("Hello")} hello();

You could pass:

function hello() {
	console.log()
}

hello();

When passing function hello() { boa shell would wait until passing the closing }.

[IovoslavIovchev]

I would recommend we also do something similar to what ghci does -- you specify the beginning of a multiline block with :{ and the end with :}. This would also be easier to implement, rather than waiting for a matching closing }.