Fix KF Track Parameter Digitization

[SClarkPhysics]

Fixes to the KF Track Parameter Digitization to remove the problem of assigning too many parameters to 0. Now implementing the digitization as:

int ix = floor(x / k)

and undigitizing as:

float x = (ix+0.5)*k;

[tomalin]

Since you're editing Track.h, please add a few comments to make it clearer what it does. e.g. At https://github.com/cms-L1TK/cmssw/blob/digitizationFix/L1Trigger/TrackFindingTracklet/interface/Track.h#L20 , say that "ipars" are digitized helix params. And just before https://github.com/cms-L1TK/cmssw/blob/digitizationFix/L1Trigger/TrackFindingTracklet/interface/Track.h#L53 make clear that the following lines return the floating point helix params by undigitizing the digitized ones.

[SClarkPhysics]

Added some brief comments as suggested, let me know if you'd like any more

[tomalin]

I made a commit to resolve the git conflict error message.