fix broken OS X build: add Json* declarations to copy constructors

Hello!

Current HEAD fails to build on OS X 10.6 with the following error:

cc1plus: warnings being treated as errors
src/effect.cpp: In copy constructor ‘effect::effect(const effect&)’:
src/effect.cpp:49: warning: base class ‘class JsonSerializer’ should be explicitly initialized in the copy constructor
src/effect.cpp:49: warning: base class ‘class JsonDeserializer’ should be explicitly initialized in the copy constructor
make: *** [obj/effect.o] Error 1

This PR fixes this in effect.cpp and nonplayer.cpp.  Please let me know if I should make any changes. 

Cheers,
Fitz