Projectors w/data arg takes 1st datum - area/line

Wrapping projector in a function that will only take the first item in the dataset
Only if the projector looks for an attribute in the data

Close #744.
Removing function check
Add built files, update test and add linePlotTests
_projectToFirstDatum method

method specifically for area/line plots to apply projectors only on first datum
Merge branch 'master' of github.com:palantir/plottable into 744-fillArea
projectToFirstDatum -> projectFromFirstDatum

Also typescript syntax for function calls
Solution encapsulated in _generateAttrToProjector

Also handles data.length === 0 case for the solution
(behavior is essentially undefined here anyways, so this gives more information on this casing)
Merge pull request #786 from palantir/744-fillArea

744 - Projectors w/data arg takes 1st datum - area/line