Adds Nickname checks, thanks @ShadowMario3 for grabbing these into separate text files from Bulbapedia.
I reordered all the encounters to match Bulbapedia; each level is denoted if different if it can be sourced from RBY.
Gen1: all are Trade1 objects, and all get the values set; just set the value in the object initializer
Gen2: all are Trade2 objects, set the same version
Gen2 all static encounters already have a version marked. Only thing remaining is to set the language.
Results in a little more code, but each path is less tangled
simplify some expressions
remove RBDragonair content in favor of a strict filter for catch rate
Move gen1 trade trainer names to stringconverter, since pk1/pk2 shouldn't refer to legality classes
