KazvIOManager accepts a url string for cacheDirectory, but the original default value is not a url. Also, KazvIOManager had its internal default directory. This is now removed, and now when calling KazvIOManager::setCacheDirectory() with an empty string, it will use the default location (<cacheDir>/imgcache).

Type: fix

BUG: https://iron.lily-is.land/T197

Open kazv with cache directory unset or set to empty. Check that no image cache is written under the current directory. Check image cache is correctly written into <cacheDir>/imgcache .