set emission rate when setTotalParticles()
add ParticleResetTotalParticles test.
Merge pull request #7607 from shinriyo/patch-1

typo function
Merge pull request #7609 from boyu0/bug5762_setTotalParticles

Closed #5762: ParticleSystemQuad::setTotalParticles() can't set a value larger than the initialized value.