Kerfly 0.15.0

Fixes from the first test on a real laser (Windows 10, LASER-M3 board).

Please update if you engrave pictures together with other elements.
In 0.14.0 and earlier, such engravings could run far too high on the bed and into the frame.

Fixed (laser output)

• Raster engraving too high on the bed. A picture was engraved too high when the layout had
  other elements too (for example a picture and a cut outline), or when the picture was scaled or
  rotated. The head could run into the frame. The trace boundary of such a layout reached too high
  for the same reason. Cut and outline engraving were always in the right place. A single, unchanged
  file is not affected and is still byte-identical to K40 Whisperer.
• Trace boundary starts where the head is. The trace used to run along the top edge to the upper
  right corner and back before going round. It now starts at the upper left corner.

New

• Safety check before sending. If a job or a trace would move the head more than 1 mm off the
  laser bed, nothing is sent, and a message says which edge and by how much.
• Head position after Stop. The K40 does not report where its head is. After a job is stopped,
  Kerfly says that the position is unknown and asks for Home before the next job.
• Progress bar with percentage. The bar fills as the data are prepared and sent. The small moving
  bar on its right still shows that Kerfly is working.

Fixed

• The diagnostic log no longer repeats the same status message thousands of times, so the report
  (Help → Save diagnostic report) again covers the whole session.

Install / update

See INSTALL.md
(Polish).
Existing installations update with git pull, or download the source code below. The start
script installs any new libraries.

Full list of changes: CHANGELOG.md