Add YEAR_WITHIN checks to getPanelData / Vnames.  Also change selection/formation of YEAR in straight projections.

Had to add YEAR_WITHIN for Georgia.  The YEAR issue came up with EOCT
Lit subjects where we use two priors from the same year/grade.  Need to
use the yearIncrement function rather than just taking the head/tail of
the sgp.panel.years
Fix the test.projection.iter function so that it takes only a single (full canonical) projection iteration.  Then force sgp.exact.grade.progression to FALSE