Corrected the auto save events order
The order of auto save events that I defined in the last commit was not quite correct. In the original code it is:
1. queue chunks for saving
2a. set delay of the FileIOThread and wait until chunks are written
2b. clear the RegionFileCache in order to flush the streams and close currently opened region files
3. call the WorldSaveEvent
... for each world. MinetickMod will follow this order too now