Brought in files from pbhogan/Signals, successfully compile with GCC and Clang
Tweaked modernimpls' internal logic, exposed set_form back-and-forth segfault
Segfault was a false alarm, signal works
Added signal/slot logic to base_pokemon_modernimpl and team_pokemon_modernimpl copy constructors and assignment operators
Fixed base_pokemon_modernimpl assignment operator and confirmed signal/slot code works with MSVC
Merge branch 'sigslot'