Unify INI values

[hansu]

Fixes #3238 and #2335.

To be done

• Adapt Gmoccapy - change spindle => spindle_0 in *.ini files #3488
• Update sample configs for DEFAULT_LINEAR_VELOCITY [TRAJ] -> [DISPLAY]
• Increase INI file version and set up update-ini script

[zz912]

* [ ]  Adapt [Gmoccapy - change spindle => spindle_0 in *.ini files #3488](https://github.com/LinuxCNC/linuxcnc/pull/3488)

Feel free remake (or close) #3488 how you need. Git is not my friend, so I cant help you.

#3488 also does:

• INI file from PNCconf is more verbose in build_INI.py
• correct MACHINE in 7_axis.ini
• correct MACHINE in 6_axis.ini