Bug 1237 - code cleanups related to includes

src/antenna/model/angles.cc

src/antenna/model/cosine-antenna-model.cc

src/antenna/test/test-angles.cc

src/applications/model/onoff-application.cc

src/applications/model/packet-sink.cc

src/applications/model/udp-client.cc

src/applications/model/udp-trace-client.cc

src/buildings/model/building.cc

src/buildings/model/buildings-propagation-loss-model.cc

src/buildings/model/itu-r-1238-propagation-loss-model.cc

src/buildings/model/oh-buildings-propagation-loss-model.cc

src/buildings/test/buildings-shadowing-test.cc

src/config-store/model/config-store.cc

src/core/examples/sample-random-variable-stream.cc

src/core/examples/sample-random-variable.cc

src/core/model/callback.cc

src/core/model/command-line.cc

src/core/model/default-simulator-impl.cc

src/core/model/global-value.cc

src/core/model/int64x64-128.h