### deep*(object, path[, value[, overwrite]])* Follow a path deep into an object, creating intermediate objects or arrays as necessary. If value is specified, sets the value of that key if unset. If overwrite is true, sets even if the value is already set. Returns the root object on set, or the current value on get.
function(object, path, value, overwrite){
		overwrite = overwrite || false;
		value = value || null;

		// Break the path, if it's not already an array.
		path = underscore.isString(path) ? path.split('.') : underscore.isArray(path) ? path : [];
		// Get the next step
		var part = path.shift();
		// Different behavior depending on if we're at the last step
		if(path.length) {
			// More children, so make sure there's a container at the next level
			if(!object[part]){
				object[part] = !underscore.isNaN(+path[0]) ? [] : {};
			}
			// Recurse, returning either the object or the old value
			var next = underscore.deep(object[part], path, value, overwrite);
			return value ? object : next;
		} else {
			// If no value, return the part.
			if(!value){
				return object[part];
			} else {
				object[part] = overwrite ? value : (object[part] || value);
				return object;
			}
		}
	}