Ensured new replays get added to the cache
Ensured loading the replay menu now is faster
Ensured deleted replays are handled correctly
Use this command on unix to drop the HDD cache:
```
echo 3 | sudo tee /proc/sys/vm/drop_caches
```
In order to test for the bug described in #4320, change `GetDirectoryName` function to return `replêys` (i.e. ^+e).