remove "~" from Plugins menu title

"~" was visible if the menu was in tearoff state.
avoid a warning under perl 5.18.x

Previously the code used to emit a number of "Use of each() on hash
after insertion without resetting hash iterator results in undefined
behavior" warnings.
make sure Makefile.mapfiles variables do not overwrite Makefile ones
new make var CONVERT_RADWEGE
data update (u.a. updates around Finowkanal)