Added new grammar for dicts, where assignment operators are streamlined
- and a new quoted assignment is add:

var obj = #[
	prototype ^= aProto
	x = 7, y = 7 // Commas are optional
	toString => "" + x + "," + y // Quoted assignment
	printTo => { // Single parameter (aStream) behavior
		:aStream.put(x)
		:aStream.put(y)
	}
]

Signed-off-by: Jakob Brandsborg Ehmsen <jakobehmsen.github@gmail.com>