Boundary checking for Color

Hello,

I'd like to suggest some extra validation for inputs given to `Color`. Since hue is a periodic value, that would mean wrapping negative values. For other inputs, that would be clamping to the lower and upper bounds of the range.

```lua
local x = Color(-3, 255, 257)
local y = x.rgbaPixel
local z = Color(y)

print("RGB boundary checking.")
print(string.format("%08X", y)) -- FF01FFFD
print(string.format("%d, %d, %d", x.red, x.green, x.blue))
print(string.format("%d, %d, %d", z.red, z.green, z.blue))

-- The % operator is floor modulo in Lua.
local u = Color{ h = -18.0, s = 1.2, v = 1.0 }
local v = Color{ h = (-18.0 % 360.0), s = 1.0, v = 1.0 }

print("\nHue boundary checking.")
print(string.format("u hue: %d", u.hsvHue))
print(string.format("v hue: %d", v.hsvHue))
print(string.format("u sat: %d", u.hsvSaturation))
print(string.format("%d, %d, %d", u.red, u.green, u.blue))
print(string.format("%d, %d, %d", v.red, v.green, v.blue))
print(string.format("%08X", u.rgbaPixel)) -- FF00B4FF
print(string.format("%08X", v.rgbaPixel)) -- FF4C00FF
```

As it stands, there is overflow when a color is converted to an integer. It looks like there may be some boundary checking for other arguments given to HSV conversion, such as saturation.

I'm referring more to the public-facing `color_class`, not to internal `color` class methods: https://github.com/aseprite/aseprite/blob/6b2c296ef0c00a42d76d3f76ecf6efb50009a88a/src/app/script/color_class.cpp#L38 .

Thank you for considering this idea.
Best,
Jeremy