Finally solve the bug on Samsung Android 9 and 10 phones that the Dialogs Main & patterns wouldn't be modeless: move the setting of this flag earlier, to the 'onCreateDialog()' function.
Minor.
Only 2 dialogs are modeless now: MAIN & PATTERNS
Lots of bugfixes.
Move to AndroidX, target API level 29.
Improve the Effects Dialog so it looks good on 'thin' screens ( 720x1440 )
Improve the About dialog.
1) Relax requirements as to OpenGL ES ( now only 3.0 required )2) fix a crash in Solving state
(Hopefully) make the Dialogs NOT disappear on clicks outside (previously this wasn't working on Android 9).Lower API requirements to 21.
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