Combinations can be deleted individually

A new feature in version 1.52.0 makes it possible to delete combinations individually. This is especially useful for solving large puzzles! Also in this version:

• The general settings are now split over two pages, instead of having all settings on one long page.
• 8x8 puzzles are generated faster, with less load on the battery.
• The puzzle generator observes the difficulty weighting more closely for all puzzle sizes up to 8x8.
• Small cosmetic improvements.