implement `fromCenter`, allowing placement along line between center and boundary point
make 'inset' (distance from corner in ne, nw, se, sw placements) configurable

Conflicts:
	src/placementcalculator.js
JSHint fixes

so that the build will run
Merge pull request #1 from nrabinowitz/inset-fromCenter

Add "inset" and "fromCenter" config settings