Generalize mortalityTables.list and mortalityTables.load

- mortalityTables.list and mortalityTables.load can be given multiple packages (defaults to "MortalityTables" and "MortalityTablesPrivate")
- mortalityTables.load supports wildcards in its default call (no need for the wildcard=TRUE argument)

Move anwartschaften.R to the pensionstafel project (forgot to update build system)