LinearGradient: Init with stops

[JoachimM7]

I would suggest the following additional init in LinearGradient.swift:

/// Inits a LinearGradient with a degree (optional) and with multiple Stops
///
/// - Parameters:
///   - degree: (optional) If 0, the Gradient is drawn from the left to the right. 90 is from top to bottom
///   - stops: An array of Stop (Stop has two properties: offset as Double (between 0 and 1.0) and color as Color)
public init(degree: Double = 0, stops: [Stop]) {
	self.x1 = degree >= 135 && degree < 270 ? 1 : 0
	self.y1 = degree < 225 ? 0 : 1
	self.x2 = degree < 90 || degree >= 315 ? 1 : 0
	self.y2 = degree >= 45 && degree < 180 ? 1 : 0
	super.init(
		userSpace: false,
		stops: stops
	)
}

Then you can use something like:
LinearGradient(degree: 270, stops: [Stop(offset: 0, color: Color(val: 0x123123)), Stop(offset: 0.4, color: Color(val: 0x123456))])

[ystrot]

This fix available in master version and will be part of 0.9.2 release.