Khan/khan-exercises — pull request #24598 by beneater (2012-06-22 04:12:16+00:00)
Title: Fix some issues with parabola_intuition_3 introduced by refactoring of i...

...nteractive.js

fix #13724; fix #24378; fix #24587; fix #24585; fix #24576;
fix #24549; fix #24512; fix #24485; fix #24467; fix #24452;
fix #24435; fix #24393

Fixes:
* Apparently old issue #13724 where the distance calculation in the hints was sometimes backwards.
* Proper implementation of custom answer validator (not done in an ideal way in some old pull request)
* Hover distance graphic thingie was always pointing up since switching from MovableLine to MovableLineSegment
* Hint animation of directrix wasn't working after refactor
* Timeline position of directrix wasn't working after refactor
* No longer dependent on KhanUtil.tmpl.getVAR()

@xymostech review?