Fixing a comment.

 	modified:   libwm/include/world_model.hpp
Adding support for expiration and deletion with new standing queries.

	modified:   implementations/sqlite3_world_model.cpp
	modified:   libwm/include/standing_query.hpp
	modified:   libwm/src/standing_query.cpp
Merge branch 'master' into refactoring
Fixing for Ubuntu!
Merge branch 'master' of github.com:OwlPlatform/world-model
Fixing build errors.

	modified:   implementations/sqlite3_world_model.cpp
	modified:   libwm/include/standing_query.hpp
	modified:   libwm/src/standing_query.cpp
Merge branch 'master' of github.com:OwlPlatform/world-model