[Ohrrpgce] SVN: teeemcee/11507 Thingbrowser & sprset browser left/right keys now always move in linear

[subversion at HamsterRepublic.com]

teeemcee
2019-12-26 18:39:03 -0800 (Thu, 26 Dec 2019)
223
Thingbrowser & sprset browser left/right keys now always move in linear order

Added linear_left_right arg to plank_menu_arrows

This fixes lots of misbehaviour when spriteset sizes are uneven and on the
last row of things.
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U   wip/drawing.bas
U   wip/plankmenu.bas
U   wip/plankmenu.bi
U   wip/thingbrowser.bas