PurrGress Major 0.6 Update

CHANGELOG v0.6.0 English (major break of the command protocol + removal of the byte codec — the actor model is now 100% actor) launch - now self.main_train.extend_from_slice(branch), instead of self.main_train.extend(branch.clone()), since branch (RouteBox) supports Copy in PurrSiding, main_train renamed to main_line in PurrSiding, change_rule - cut in the usual sense in PurrSiding, the switches field completely removed as unneeded and inconvenient in PurrSiding, cut: find_index_f...