Make lighters variable-charge-when-spawned.

This severely reduces the chances of finding a "full" 100-charge lighter by biasing the random generator toward producing more low-charge lighters.  There's about a 50% chance of making them between 1-22 charges, and about 75% to be between 1-67 (unless I'm doing my statistics wrong, which I may well be doing).

Mostly addresses issues like #8893 (and related complaints) by making the lighters you find be either shoddy or partially used, whichever way you prefer to imagine it. Sometimes a lighter will have just one charge left -- you could pretend the striker had just one good light left in it, and that was it.

Cheap lighters, in my experience, tend to vary a lot in quality; refillable lighters are untouched by this, and should be a much more reliable source of fire for players, along with matchbooks (which also always have all 20 charges... for now).

Many thanks to @BevapDin for help in finding JSON features that already existed and allowed this.