Fix: permission check for integer flags

[RedstoneFuture]

Overview

Commands like /p f s mob-cap 0 are now allowed, if the player hast the permission plots.set.flag.mob-cap.0 ore higher. Zero is not a valid range for the permission check.

Fixes #3896

Description

• Changing integer check to allow zero
• Adding small comments to describe the complicated algorithm
• Adding details to the max-plots setting description as it stands for more than just the plot-maximum (probably historically formed)

The permission check was tested in-game.

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