Small update - NEXXT 3.1.1 released

This new version doesn't change much. 
But one good reason to upgrade from 3.1.0 is that quick multiline is now available by hotkey, making it more accessible to plot a line without having to switch drawing tools. 

Changelog:

====
3.1.1 
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Improvements:
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• Modifier key for Quick Multiline:
  It's now possible to simply hold [Alt] and click twice or more to plot a "quick multiline",
  or a series of them.
  
  This is akin to holding Shift in Photoshops' or Aseprites' respective pen/brush modes.
  Previously, this tool was accessed only through having the normal Line tool ON [N],
  and shoosing "quick multiline" mode in the line toolbox [Shift+F5].
  
  Accessible in the CHR editor, as well as on the tileset canvases while in draw mode.
  
  Advanced tip: while accessing quick multiline this way hides some of its fancier features from the toolbox,
  you can still, while holding the click button down, release [alt] momentarily to access other hotkeyed
  features, such as [shift] for or [shift+alt] for relative ink modes.

Bugfixes:
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• Menu > Save patterns (.chr) > Save 4 sets (A...D):
  A faulty flag made it save set A four times in a row instead of all 4 sets.
  Fixed.

Minor changes:
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• Error message when an external system palette couldn't be found has been clarified (and no longer contains garbage characters). 
• Moved the "Find" submenu back from the "Select"- to the "Patterns" menu.