-Updated configure.ac to check for the following libraries:
-libGL
-libGLFW
-libSOIL
-BulletDynamics(libbullet)
-libGLEW
-libGLU
-libGLM

-Note: currently do not check for BulletCollision, BulletSoftBody, or Bullet's LinearMath directly.
-Just some revisions to the error msgs