- Use a global pointer for the current sanitized command
- Pre-sanitize the current command to bypass `N` and nullify `*`,
removing the need for handlers to bypass, ignore, or nullify these
parts, and reducing overhead for `code_seen`, etc.
- Pre-skip leading whitespace.
- Only look for G, M, T codes at the start of the command.
- Verify that G, M, T codes are followed by command codes.

Name magic value 20 to MAX_OVERSHOOT_PID_AUTOTUNE

to make it better findable.

Have G92 set the nozzle position on Delta and SCARA

rework out_bits

Code style and a dangling "else"

Rename gCode to codenum as a consistency

Hide M117 with no LCD

Add gcode_line_error to reduce code size

Rename process_commands to process_next_command

Tweak to fan kick routine

NO_TIMEOUTS and ADVANCED_OK off by default

Allow lsDive to recurse with minimal stack usage

add plan buffer remaining for 'P' and block buffer remaining 'B'

Display unknown XYZ on the LCD as "---"

Use MSG_OK in M105

Use Mendel default for INVERT_Y_DIR

Consolidate arc code, remove motion_control.*

- Also show 2 digits past decimal for Z on DOGM

Formatting tweaks