Add support for THT Resistor Color Code Markings

[Electro707]

Related to https://github.com/yaqwsx/PcbDraw-Lib/pull/19, this PR allows PcbDraw to, if the component it's drawing is a THT resistor, to auto-detect the resistor value and change the band's color to reflect that:

The resistor's values can also be set manually with the resistor-values argument, input given as comma delimited key-value pairs that are colon delimited, for example resistor-values R1:1k,R2:20k.

The colors of the bands are in the default board style. If a board style doesn't have this (or any keys), it will get copied from the default style.

Closes https://github.com/yaqwsx/PcbDraw/issues/71

TODO:

• [x] Add option to "flip" the resistor, which would just flip the colors on the bands
• [x] Perhaps there is a better argument input style for the resistor-values
• [x] Add tolerance parsing
• [x] The resistor band colors are stored in the board style. Should this be moved to it's own style input?
• [x] If a board style doesn't have a key, it will be copied from the default style. This might be undesired. Thoughts?
• [x] Create test boards with just resistor and create a test script to verify it all works
• [ ] Document this feature
• [ ] Wait until https://github.com/yaqwsx/PcbDraw-Lib/pull/19 is merged to update the version used in this repository

[Electro707]

Removing the WIP tag as most of what needs to be done should be up for discussion.

[yaqwsx]

Thank you for your effort! Here are my thoughts on the topics:

• Perhaps there is a better argument input style for the resistor-values: It would be nice to allow for both; direct and file input. However, as I plan major rework of the CLI in the future, is it fine for me to leave this as it is. In the future, we could read the values from schematics.
• The resistor band colors are stored in the board style. Should this be moved to its own style input?: Having it inside the style is OK for me. Once we rework the CLI, we could introduce style inheritance, just like KiKit does with panel configurations. That would solve this issue.
• If a board style doesn't have a key, it will be copied from the default style. This might be undesired. Thoughts?: As I wrote in the comment in the code - it is OK for me if we also check for extra keys in the style. The reason for that is to catch typos in key names.

I also have one suggestion: Currently, you use opacity to disable the bands. I was thinking of using display="none" instead. It is easier to see and we could implement bands that are semi-opaque. Also, I guess display="none" might be more efficient on rendering. What are your thoughts?

[Electro707]

If a CLI rework is already in the plans, then having it as a direct argument instead of a file is fine.

I do like the idea of changing the display property instead of opacity, so I changed that in e01e3b0 and the component library.

[yaqwsx]

Hi, do you plan to incorporate any changes? If not, I will give the code final proof-reading and testing and we could merge this!

[Electro707]

I don't see any more changes that can be added

[yaqwsx]

Looks good to me. Could you rebase is to master? Then I will merge this.

[Electro707]

Rebased to master, also updated the footprint library to point to master of pcbdraw-lib