Fix uninitialized variables in ParticleEmitter. Closes #981.

Source/Urho3D/Graphics/ParticleEmitter.cpp

@@ -46,6 +46,8 @@ ParticleEmitter::ParticleEmitter(Context* context) :
     emissionTimer_(0.0f),
     lastTimeStep_(0.0f),
     lastUpdateFrameNumber_(M_MAX_UNSIGNED),
+    emitting_(true),
+    needUpdate_(false),
     serializeParticles_(true)
 {
     SetNumParticles(DEFAULT_NUM_PARTICLES);