search: made separate functions for encoding cbfs in xEstimateResidualQT()
search: made a function for null cost calculation in xEstimateResidualQT()
[REVIEW PATCH/OUTPUT CHANGED]search: removed multiple encode Coefficients from estimateResidualQT()

Tried to remove multiple encode coefficients from estimateResidualQT() function.
Coefficients are encoded in three stages: Once for calculation of distortion and twice for split and unsplit
block cost calculation. I have given comments where I have changed the code.
fix typo