Either warn or convert DialogBlocks binary .pjd files

[KeyWorksRW]

Description:

Unfortunately DialogBlocks does not add any special header to their binary version of a .pjd file., so until you read it you don't know if it is an XML file or a binary file. However, I think we can read the first 4 bytes and have a reasonably good idea as to whether it is an XML or binary file. Unless we add the ability to process the binary file (see below) then we should display a message to the user telling them that it is binary and how to get DialogBlocks to save it as an XML file.

It looks like the binary file uses a small set of flag bytes followed by a size_t flag. That size_t flag could probably be paired with a XML name string which means we could easily convert it into an xml name and use both flags to create an XML file in memory and then process it as if we had read an XML file.