HWLED mode: support for RGBW, RGBWW, RGBWWA

[DangerousPrototypes]

WS2812 scriptable opportunity

Support for RGBW might be possible with minimal change, but still only support a single LED.
Support for multiple LEDs requires buffering all the data between a start / stop character, and sending it all at once, because the timing of these chips is very sensitive.

New recommended method for scripting output:

• [ or { to indicate a start of a new data buffer to send to the WS281x strand. The data buffer is zero'd out.
• Individual bytes of data to indicate raw data to encode into WS281x format. These bytes are simply copied into a pre-configured data buffer, and the count of used bytes in that buffer is incremented.
• ] or } to finish the data to be sent to the strand ... which also kicks off the tranmission of the used bytes in the data buffer.

With these changes, arbitrary length and/or color format (RGB, RGBW, RGBWW, RGBWWA) strands would be supported.

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What do those RGBWWA letters mean...

• RGB == Each pixel has a Red, Green, and Blue led. Note that this designator is often used, even if the order in which the colors are sent varies. For example, the onboard pixels on the BP require the bytes in the order GRB. Each pixel is sent three bytes of data.
• GRB == See RGB. This designator explicitly defines the order in which the bytes must arrive (green byte, then red byte, then blue byte).
• RGBW == Each pixel has a Red, Green and Blue led, as well as a single white led. The color temperature of the white led (e.g., generally either cool or warm) is not specified here, nor is the order in which bytes must be sent. Each pixel is sent four bytes of data.
• RGBWW == Each pixel has a Red, Green, Blue, Warm White, and Cool White led. The order in which the bytes must be sent is not specified. Each pixel is sent five bytes of data.
• RGBWWA == Each pixel has a Red, Green, Blue, Warm White, Cool White, and Amber led. The order in which the bytes must be sent is not specified. Each pixel is sent six bytes of data. Strands with this configuration may have high CRI, aiming to be suitable for general indoor lighting replacement purposes.

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