Gosu::Color should implement Gosu::Color#argb

[mblumtritt]

Since Gosu::Color.new accepts an argb value the instance should be able to return this value.

A method Gosu::Color#argb would be fine, maybe Gosu::Color#to_i is acceptable for this.

There is only an Gosu::Color#abgr which is not accepted by any Gosu::Color method. (Where is this helpful?)

[jlnr]

In theory there is a Gosu::Color#argb method, but in practice SWIG has merged it with the class method of the same name:

irb(main):004:0> Gosu::Color.argb
ArgumentError (Wrong arguments for overloaded method 'Color.argb'.)
Possible C/C++ prototypes are:
    std::uint32_t Color.argb(Gosu::Color const *self)
    Gosu::Color Color.argb(Gosu::Color::Channel a, Gosu::Color::Channel r, Gosu::Color::Channel g, Gosu::Color::Channel b)
    Gosu::Color Color.argb(std::uint32_t argb)

I'll export it in SWIG as #to_i to prevent this from happening, and then alias it to #argb as well.

There is only an Gosu::Color#abgr which is not accepted by any Gosu::Color method. (Where is this helpful?)

I think this is from when Gosu still had a Direct3D backend. There's also a #bgr method that I think was only ever useful for Win32 programming:

irb(main):006:0> Gosu::Color::FUCHSIA.bgr
=> 16711935

Maybe I'll kick them out at some point in the future.