Removed no-op class STM engine that was left over from engine-choice times
Dropped last user of input::Method and deleted the class
Simplified engine_stm and input code
Converted input link modules to use std::unique_ptr instead of std::auto_ptr
Simplified InputBase class
Refactoring: Migrated the STMEngine to FilterFactory
Simplified the ResolutionSetter unit test
Dropped the unused MetaInfo reference from the FilterFactory interface