Bullet update: new collision functions:

* rigidbody_world.collision_pairs
* Added 2 param to rigidbody_world.convex_sweep_test()

Squashed commit of the following:

commit bd609f5abf4458cda154455585078492beb94447
Author: Benoit Bolsee <benoit.bolsee@online.be>
Date:   Mon Jan 6 10:28:09 2014 +0100

    Frame range of rigid body simulation is automatically adapted from scene
    range.

commit 22303c34f147e8522f9d7acff51055cb6ce25cad
Author: Benoit Bolsee <benoit.bolsee@online.be>
Date:   Sun Jan 5 18:29:54 2014 +0100

    Fix segfault in convex_sweep_test when the object has no physics shape

commit 0d68f7d89f3d2657d7e4a3a6dfb3de0e797b47db
Author: Dalai Felinto <dfelinto@gmail.com>
Date:   Sat Jan 4 18:25:18 2014 -0200

    make sure collision_pairs is initialized as NULL

commit f55c31ac169227dfb9bea573c5bd89fc2bffc559
Author: Dalai Felinto <dfelinto@gmail.com>
Date:   Sat Jan 4 13:59:14 2014 -0200

    Skip function for Collision Pairs

    Make sure the pass works even if the objects are removed middle way through the
    interaction

commit d1c7b65f1d485e6a5d76664bd558e5d98517f8bf
Author: Benoit Bolsee <benoit.bolsee@online.be>
Date:   Sat Jan 4 13:30:48 2014 +0100

    Add BKE_rigidbody_update_collision_pairs()

    This function loads the list of collision pairs from bullet. Should
    be called after a simulation step. Beware that simulation pointcache
    does not store the collision pairs. Hence this list is not updated
    if you change the frame number backward and load the object position
    from the cache.
    It is best to force a cache clean first to make sure that the rigidbody
    simulation is executed.

commit a529d656be05b9d3bc533360413b9bbc345186e9
Author: Dalai Felinto <dfelinto@gmail.com>
Date:   Fri Jan 3 11:41:43 2014 -0200

    create ListBase for RigidBodyWorld collision pairs and RNA

    @ben2620 check the notes in
    rna_rigidbody_collision_pairs_begin

commit 0956bfac1186bd6d911860abd12f3e6124c37bb5
Author: Dalai Felinto <dfelinto@gmail.com>
Date:   Thu Jan 2 21:26:14 2014 -0200

    make boolean parameters boolean

commit 6eabff94f1daf726c8fbc50f6d2690446ee54dda
Author: Benoit Bolsee <benoit.bolsee@online.be>
Date:   Mon Dec 30 12:12:46 2013 +0100

    bug fix: ignore self object in convex_sweep_test.

commit ad2185abff85d4b8f480b8a569444bac465a202e
Author: Benoit Bolsee <benoit.bolsee@online.be>
Date:   Sun Dec 29 11:56:24 2013 +0100

    new RB_dworld_get_collision_paris() to report the collisions that occurred
    in last frame.

commit 6e794c3deab6be57c283021cd193eba2413200e5
Author: Benoit Bolsee <benoit.bolsee@online.be>
Date:   Fri Dec 27 17:46:31 2013 +0100

    Add 2 param to rigidbody_world.convex_sweep_test:
    col_groups to indicate which groups we want to test
    use_sensor to indicate if we want to detect sensor objects (default no)
    return is a 5-uple, last value=reference to object hit (only if 4th
    value=1)

commit 4c6b21beeeb24225591e939878faa97c61a99afb
Author: Benoit Bolsee <benoit.bolsee@online.be>
Date:   Thu Dec 26 13:49:38 2013 +0100

    Add sensor physics type.
    A sensor can collision with any other objects, including other sensors
    but does not restitue any force. Collision is controlled by a new
    setting: collision mask. A sensor collides with another object
    if the object group is part of the its mask.