Allow resizing a Cache without clearing queued glyphs

The documentation for Cache::cache_queued says "Caches the queued glyphs. If this is unsuccessful, the queue is untouched". It would be nice to use this to write code like

for (font, gly) in glyphs {
    cache.queue_glyph(font, gly);
}

while cache.cache_queued(...).is_err() {
    cache.resize(double(cache.dimensions()));
}

However there is no way to increase the size of the cache without losing the queue, so we have to recreate the queue each time

It also occurs to me that set_position_tolerance and set_scale_tolerance are not quite equivalent to recreating the cache since they do not touch the queue. Maybe they could be un-deprecated with a performance warning?