$700 controls whether they are scanned for internally in the main program (1) or always located externally (0).
If scanned for internally the program is run twice, initially in check mode to locate the subroutines before it is rewound and run in normal mode.
If stored externally the file P<macro number>.macro is run, <macro number> is the M98 P value.
Removed IDLE state requirement for executing G65 macros, an error will no longer be returned and the macro will be run.
Added event handler for outputting welcome message on "native" USB connect for drivers that provides the linestate changed event.
Sub name matches filename with extension .macro.
Added core event for handling special gcode comments used by expressions and flow control: DEBUG, PRINT and ABORT.
Added overrideable default $-setting values for second PWM spindle to grbl/config.c.
Added support for LinuxCNC style (ABORT,<msg>) comment, requires expressions enabled. Terminates gcode program, outputs message and returns error 253.
Added PRM[<setting>] and PRM[<setting>,<bit>] functions to expressions, returns $-setting value or value of bit in integer type setting.
"hardened" flow control code, fixed bug in repeat...continue handling.
Changed signature of grbl.on_gcode_comment event, now returns status code.
Fixed incorrect comment string passed to passed to grbl.on_gcode_comment event.
Added generic redirector for temporarily changing input stream to read from a file. Supports nesting.
Added clear of return value on CALL statement and added optional return value expression support to ENDSUB.
Improved handling of multiple simultaneous spindles. Still work in progress.
For developers: moved user M-code entry point hooks from the HAL structure to the core handlers and changed signature of the check() function to better support valueless words (letters) when parameter support is enabled. Removed deprecated parameter from the validate() call signature.
Added named parameters for getting absolute (G53) position: _abs_x, abs_y, ...
Available when expression support is enabled.
Changed stepper enable HAL signature to allow current reduction when idle.
Added reference id to spindle registration in order to allow configuring default spindle, and possibly additional spindles, at compile time.
Added experimental support of LinuxCNC style subroutines.
Available for gcode run from local filesystem such as on a SD card or in littlefs.
Improved handling of G92 when G92 offset is changed while motion is ongoing. Ref. issue #241.
Fix for issue #521, crash when running G65 macro on ESP32.
"Hardened" stream switching code, likely fix for discussion #456.
