v0.20.0: screen aligned grid, flex-paste, named palette exports

0.20.0 is here.

I'll let the video present the more significant changes. Changelog attached below!

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0.20.0
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New features:
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Flex-paste CHR:
-If making a box selection larger than 1 tile (or 2 tiles if in 2x2 edit mode),  pasting tiles will place those tiles inside the boundaries of the new selection. This can for example be useful to put disorganized tiles into a section, change orientation of order,convert a strip of tiles to a box of tiles, or vice versa. 

Tip: Don't worry about making the selection larger for pasting: the paste won't replace more tiles than what is queued up by your previous copy action.

Tip: Be aware that a selection box smaller than the # of tiles copied will ignore the excess. The best way to proceed if dissatisfied with your first paste in this case is to make a larger selection and paste again - especially if you copied with cut and don't want to lose content.

Tip: A single tile selection behaves as normal/before (representing the origin to paste to).

Screen aligned 4x4 grid option:
-If both "x4" and "Scr" buttons are down, then the 4x4 grid aligns to the start och each screen. This is often useful when laying out level content or the like, since an NES nametable/screen is an "imperfect" 32x30 tiles

Improvements:
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Multi select + copypaste + masks:
-Bitplane masks and colour protection masks now work for serial  (usually multi-selected, then copied) clipboard contents.

Putting subpalettes to clipboard:
-If either as C or ASM data, session name and set ID is now included in the header/label by default.
-If as ASM data, the clip is now more readable; putting each subpalette on its own .byte row.
-From preferences (ctrl+p), you can set whether or not to include session name and and subpalette set in the label/c header.

Bugfixes:
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Display bug:
-Navigator, making a new selection after a paste or cut:  the canvas wouldn't fetch a fresh buffer, leaving traces of the old selection rectangle behind. Now fixed.

Navigator window sizing:
-Now behaves better when you have canvas sizes larger than what fits the screen height of your main screen.

Pasting serial CHR:
-Pasting from serial CHR clipboard contents (usually from a multiselected cut or copy) didn't set up and undo event. Now corrected.

Copying undo bug:
-CHR copying set undo regardless if a cut or not was made. Now fixed.