Feature/check nveg

[tbohn]

• addresses Potential bug in image driver handling of parameter file, and/or tonic #787 but doesn't close it
• tests passed
• new tests added
• science test figures
• ran uncrustify prior to final commit
• ReleaseNotes entry

Just added a minor check to vic_init() that for each cell, nNonzero <= nveg, where nNnonzero is the number of veg tiles with Cv > 0. nveg is allowed to be greater than this number due to potentially adding extra tiles for bare soil and above treeline vegetation. But nveg from the parameter file should never be less than nNonzero.

Also modified warning messages for when either Cv or root_frac don't sum to what we want them to. These messages now use format .16f to show the user more precisely what the sum comes to.

The motivation for this new check is that the logic for the mapping between veg_con_map and veg_con relies only on Cv to decide if a veg tile is valid. Yet elsewhere in the code, nveg is used. It's possible that these two quantities could get out of sync for a variety of reasons, which would result in assignment of unintended parameter values (from invalid tiles) to the veg_con structure. This check avoids that and ensures internal consistency.