+2006-05-09
+ * changed level file format by adding two new chunks "CUSX" (for custom
+ elements, replacing the previous "CUS4" chunk) and "GRPX" (for group
+ elements, replacing the previous "GRP1" chunk); these new IFF style
+ chunks use the new and flexible "micro chunks inside chunks" technique
+ already used with the new "CONF" chunk (for normal element properties)
+ which makes it possible to easily extend the existing level format
+ (instead of using fixed-length chunks like before, which are either
+ too big due to reserved bytes for future use, or too small when those
+ reserved bytes have all been used and even more data should be stored,
+ requiring the replacement by new and larger chunks just like it went
+ with "CUS1" to "CUS4"); this whole problem now does not exist anymore
+