#24 Savegames use PElist numbers

[Joseph P Morris]

Savegames store the PEscript ID numbers in the file. This is not safe since adding new scripts to the game will renumber them.

One option is to convert the file formats to save the name instead, but a more backwards-compatible solution might be to save a .PEL file for each map containing the PEscript names and numbers. This can then be used on reloading to ensure the numbers match the ones currently used by the game.