Correct color names and hexadecimal codes

[LDmicroGitHub]

Hello, Peter.
I propose to correct the color names and hex codes according to base colors from
https://en.wikipedia.org/wiki/Web_colors

I think all hardware manufacturers are guided by these hex values.
Also, some used color codes are unsafe if RGB565 or RGB444 converting used.
100=0x64 and 90=0x5A will lose the lowest bits when converting to RGB565 or RGB444.

I am not sure about the synonyms of colors. Probably they are not needed.

I haven't changed yet the else part of color definitions.

This pull request leads to some corrections in documentation and code due to the change in user colors.

Also, I propose to develop several color schemes similar to those used in editors with good contrast and readable.

I want to know your opinion on the main.
WIP

[LDmicroGitHub]

micropython-nano-gui\gui\demos\check_colors.py

[peterhinch]

My initial reaction is not one of enthusiasm. It will break users' applications and my test scripts. It will need to be tested on different displays: some drivers reduce the rgb() values to 8 or 12 bits. Some of my colors were chosen for specific results in my test scripts. There's a lot of work in checking all that...

I do take your point in the code comments about light and dark. I didn't choose my names wisely.

On the other hand I can see merit in standardising colors. Perhaps the best option is to produce a web_colors.py (or whatever name you think best) which can be renamed and swapped for my version. Then users have a choice.

[IhorNehrutsa]

Well.
I understand your initial reaction. Backward compatibility is very important.
Let's see what we can do.

I reverted the colors.py but left comments.

1. I propose to rename
   LIGHTRED as DARKRED with the accompanying comment
   There aren't LIGHTRED in other places of the repository.

2. DARKGREEN is present, so LIGHTGREEN rename to the
   SILVER = create_color(9, 0xC0, 0xC0, 0xC0)
   There are LIGHTGREEN in
   micropython-nano-gui\gui\demos\fpt.py
   micropython-nano-gui\FPLOT.md