Refine Practice Robot Code

[rguinn2338]

This pull request refines the current codebase and adds several changes based on feedback from the meeting on Saturday 2/5.

The changes are made on top of the most recent working code (tag 2-6_working)

Changes:

• Motor speeds tuned to tested speeds
• Commands added based on intended mechanism use
• Inputs updated to match driver preference
• extraneous commands removed
• null checks replace global bool checks