Setting data projection locations

[chrispbradley]

The ability to set the projection location of a data point directly doesn't work. The ResultXiSet call sets the data projection result xi array but the fitting uses the data projection result elementXi array.

[chrispbradley]

Add new routines to set the result xi via ResultElementNumber, ResultElementFaceNumberSet and ResultElementLineNumberSet calls. These calls together with ResultXiSet will specify the data projection location. A DataProjectionEvaluate call is still required and any data points that do not have their result projection location set will still be projected.

[chrispbradley]

Fixed in #177