[Tool/UI] Filters Freeze on Deactivation

[Antirhinnum]

Deactivating a filter in a spawner tool can sometimes freeze the game for a few seconds. Most obvious for the Item and Tile spawners. The issue becomes less severe as it is repeated. May be related to #5.

No other mods enabled. No errors in logs.

Reproduction:

1. Open the item spawner tool.
2. Apply the tModLoader mod filter.
3. Unapply the tModLoader mod filter. In this case, the game freezes for long enough that I almost reported this as a crash, not a freeze.

[ScalarVector1]

Almost certainly #5, its due to attempting to draw (and thus load assets for) every item at once..

[ScalarVector1]

I've implemented a temporary countermeasure for this