quant: correct QP range clipping for 10-bit input depths.

Fixes a bad hash error and artifacts introduced by commit c8973aec5e70
dpb: destroy and delete m_reconPicYuv from picSymFreeList
encoder: remove m_freeList from encoder class, the m_freeList moved into dpb
keep TComPic until next call if recpic is exported as pic_out

We must prevent the recon YUV from being recycled until the next picture is
encoded.