Rename PMAP_CONTRIB_MAXBINS to PMAP_CONTIRB_MAXCOEFFS in pmapcontrib.h, since there's no more 1:1 correspondence between bins and wavelet coeffs in the padded wavelet xform. Added check for an mRGBE data field (coefficient index) overflow if too many bins are specified. This ensures early bailout before actually distributing and building the contribution photon map. Fixed mRGBE data overflow error msg format.