Add colour preview method

[Martysh12]

Colour previews

Allows users to easily preview a colour using the Color.preview() method.

What changed?

A new preview method was added to the Color class, allowing for quick and easy colour previews.

How does it work?

The preview method uses Tkinter, which is included in every Python installation, and should be consistent across operating systems. The method creates a root window, sets its geometry, sets its title and sets the background colour to whatever colour is stored in this Color class.

Why?

I was recently browsing old projects of mine, and I stumbled across a list of Color objects. Wanting to view those colours, I searched for a quick and easy way to preview colours in Python. After failing miserably, I took it upon myself to implement a preview method for the Color class. Also, why would anyone want to implement an essential feature all by themselves?

Examples

>>> import colour
>>>
>>> c = colour.Color("#9F1231")
>>> c.preview() # Preview a single colour
>>>
>>> for i in c.range_to(colour.Color("#000"), 8):
...     i.preview(geometry=(200, 100)) # Preview a colour with custom geometry
...