Merge remote-tracking branch 'origin/2.8' into master-merge

* origin/2.8:
  docs: make an index.html page for the PDF docs
  cosmetic fix to a configure error message
  Update for new version of Rpi400
  Update for new version of Rpi400
  docs: changed url in halshow doc
  docs: created mb2hal doc based on sample ini file
  mb2hal: added pins to manpage
  docs: fixed link
  docs: include mb2hal ini file in docs
  mb2hal: updated and fixed sample configuration
  gmoccapy: sensitize save button after 'save as'
  gmoccapy: fix detection of file change
  Update ini-config.txt
  Update ini-config.txt
  Add files via upload
  correcting submakefile for 2.8
  update
  missing in documentation for INI RS274 section
  Change EDITOR = geany. Restore more generous dirhold and dirsetup timing.
  Updated the gantry example with what I gather from the forum is best practice. 1) Reduce from 4(XYZA) to 3(XYZY) coordinate. 2) Use negative HOME_SEQUENCE values for synchronous homing of the dual Y joints. 3) Rename signals such as adir, astep to y2dir, ystep.
  full update xhc-whb04b-6 for 2.8