Create an enum system for seek requests to handle different cases.

* changed m_bSeekQueued to m_iSeekQueued and made it refer to an enum
* created seekExact for hotcues, so the cuecontrol can override quantize mode
* get rid of m_bSyncPhaseQueued and made it another seek type.
* pull all of the seek logic into a separate function
* stop calling slotSeek directly!