two_level_rr scheduler completed.

Problem 1. It seems gpgpu-sim's ldst writeback doesn't call releaseRegisters(). Instead it directly call releaseRegister(). However, releaseRegister() doesn't contain a longopereg.erase. It will block two_level_rr scheduler's long op check. Hence I add longopreg.erase into releaseRegister() to solve this problem.
   However, without this correction, original three scheduler still can work. It really confuse me!!!!

Problem 2. Just a suggestion. If std::vector can satisfy the requirment, don't use std::deque. For me, some behavior of std::deque is unpredicatable. The interal mechnism of std::deque and std::vector are completely different.