fix for grad with pos control and test
Use btConvexHullShape for boxes.

The convex interface that we're using for our closest-distance computations
gives erroneous normals for box shapes. If we represent the box as the convex
hull of its vertices the normals are fine. Fixes #174.
Add test case for box-point contact normals
Update contactImplicitBrick test.

Changes:
  * Removes terrain-only flag.
  * Disable visualization by default
  * Check positions and velocities with different tolerances (as per Michael's
    email)

Now passes with tolerances 1e-2 for positions 1e-1 for velocities.
removed persistent variable
fixed typo
Merge pull request #271 from kuindersma/fix-poly-no-mail-typo

fixed typo in AffineSystem
Changed quat methods to return a value instead of working with references.
drakeQuatUtil --> drakeGeometryUtil.
Merge pull request #272 from tkoolen/drakeQuatUtil-updates

Drake quat util updates
fixed typo causing quadrotor unit test to fail
Merge branch 'poscontrol' of https://github.com/blandry/drake
use valuecheck in test
Slightly increase tol in contactImplicitBrick.
Use rel. tol. 1e-8 in ModelTest.cpp
Merge pull request #273 from kuindersma/fix-pelvis-bug

removed persistent variable
Added some rotation representation conversion utility functions to drakeGeometryUtil.
Added testDrakeGeometryUtil.
more info in knownIssue because some known issues are reporting as unknown
Rotation conversion functions, moved angleDiff. Rotation conversion functions tested in testDrakeGeometryUtil.