M220 - new parameter to exclude travel (non printing) moves

[Argo]

At the moment M220 S20 (sets speed to 20%) does also slow down travel moves.
But what if we could choose whether to slow down travel moves with M220 or not.
Slowing down travel moves has a big drawback as this can increase the chance for stringing and blobs.

For example: M220 T1
The new parameter "T(1)" would then mean, that it does exclude travel moves. This setting can be set in config.g and when there is M220 Sxx in a gcode file it uses the set parameter (T1) from the config.g unless it gets overwritten with T0.

Use cases would be modifier in the slicer software. For example a print has very fine details between specific layers so we could set M220 S50 for those layers but without slowing down travel moves.

Another use case is the Palette 2 multi color unit and their Octoprint plugin. The multi material unit needs to do splices between colour changes and printing too fast may cause a failed print as the buffer cannot keep up. That's why the Plugin has a feature to slow down prints during splicing actions with M220 which does also slow down travel moves and can cause stringing / blobs.