…close

We want to be able to compute implied oncurves both before coordinates have been rounded to integer and afterwards.
Also when ufo2ft builds interpolatable master TTFs, we want to turn off the rounding so that varLib can call dropImpliedOnCurvePoints on the un-rounded coordinates, so we need an option to disable rounding the coordinates in the ttGlyphPens

…var expects

ufo2ft will no longer send varLib already-rounded master glyf tables (to give it an opportunity to compute implied oncurves on the pre-rounded coords) so when retrieving coordinates off the glyf table in order to compute gvar deltas we have to round

ofter the rounding gives us an opportunity to make an oncurve impliable, for points that were not equidistant become so after round, so why not take it!

as Behdad suggested in review