Add support for non-integer vision range

[Jagusti]

A question: the "Normal Vision Range" in the Module's settings, is it possible to set it so we can input a value between integers? We're experimenting with having vision in darkness expand to 0.5 yards (or similar) instead of 2 yards. That's mainly because we use 1 yard square maps instead of the default 2 yards.

Originally posted by @TheFirst05 in #193 (reply in thread)

[Jagusti]

This line is forcing integer/stepped validation:

fvtt-wfrp4e-gmtoolkit/modules/gm-toolkit-settings.mjs

Line 349 in 09dc6df

s.isNumber = true

I prefer not to remove it for all cases, as integers are useful most of the time. But this is the starting point. It may be enough s.integer = true instead.