New 2F140 gripper implementation + franka2f140 robot + some changes on creating pybullet clients

[anthonysimeonov]

Overview of changes:

• Full refactor of Robotiq2F140 gripper class in eetool. Based on p.createConstraint instead of a background mimic thread. This should help the system be useable from MacOS (which has extra complications multithreading with pybullet)
• added 'server' argument to the BulletClient to create a p.GUI_SERVER or p.SHARED_MEMORY_SERVER instead of the regular modes. These are also needed for proper multithreading
• New URDF + mesh assets + cfg file for panda robot (panda.urdf, panda_2f140.urdf, franka_2f140_cfg.py)
• modified check for pulling URDFs from pybullet data, use a new 'pybullet_urdf' flag instead.
• some small updates to the franka_cfg and assets/franka_arm cfg file

[anthonysimeonov]

@taochenshh @richardrl would appreciate a review on this. @richardrl I think hopefully this should fix the issues you faced a very long time ago using this gripper on your mac.

[lgtm-com[bot]]

This pull request introduces 3 alerts when merging 83e7cb06ef27d79d0778e34ca976d5841b852a91 into ba647ee176465c26bb19ecb8bea468fe4cc1dc72 - view on LGTM.com

new alerts:

• 3 for Unused local variable

[taochenshh]

@anthonysimeonov everything seems to work except the ignore_physics might not be working properly.

[lgtm-com[bot]]

This pull request introduces 3 alerts when merging 6a0650fd6e3ecf6ad77178a5a0481a76df01aea4 into ba647ee176465c26bb19ecb8bea468fe4cc1dc72 - view on LGTM.com

new alerts:

• 3 for Unused local variable