Build order overlay

[CraftySalamander]

Prepare version 1.4.0 (main addition: new build order overlay from RTS_Overlay of CraftySalamander):

Here is a summary of the main changes

• The order of the build orders can be adapted with 'Move build order up/down'.
• Two format of build orders are available:
  • JSON format with images and resources distribution, adapted from the RTS Overlay of CraftySalamander.
  • Simple TXT format (compatible with legacy behaviour, using the same tools as the JSON format).
• New hotkeys: go to the previous/next step of the build order (only working for JSON format).
• Build order overlay image sizes can be adapted.
  • Other new settings available in the 'config.json' file.
• New overlay icon.