Incorrect generated code for optional (tagged) data members of exceptions in C#

[bernardnormier]

slice2cs 3.7 generates incorrect code for optional data members of exceptions - the optional members should be marshaled/unmarshaled after the non-optional members and sorted by tag.

For example:

exception A 
{ 
    string name; 
    optional(3) string another; 
    string m;
}

exception B extends A
{ 
    int x; 
    optional(3) int y; 
    optional(1) int z;
}