slickgrid did not have an API to specifically invalidate all async render output (now it does: invalidateAllPostProcessingResults()). Use case: we async-render cells which contain device/screen-dependent info; when the user zooms in or out, that data needs to be rerendered (e.g. when these are image thumbnails); the alternative would've been massive updateCell() calls which are far more costly as they invalidate entire rows due to their internal behavior and all we need is a rerender of specific columns only!
fixed crash in formatter due to it not having been updated to the new formatter/editor call interface