State machine dev

[AshayAswale]

State machine PR

Simple state machine works on two turtlebots

Important

• Merging this PR will stop the turtlebots to explore by default.
• To start exploration, publish 'false' on the topic ~/pause_exploration

Features

• Decentralized state machine works on two robots
• Modular approach, any state can be modified
• Adding a new state is super easy.. Barely an inconvenience!

Bugs

• If a relay is going to meet and an explorer is exploring, and by chance, relay sees explorer then:
  • Relay will switch to state 'Meet'
  • Explorer will continue exploring without the knowledge of relay being there
  • If this thing happens away from the meeting point and the explorer does not see relay while going to the meeting point then that will be the dead-
• but there are a few hardcoded names. Some rostopics and robot names are hardcoded in some places. Porting to argos khepira might not be 'out of the box'

Things not included

• Multiple turtlebots are not tested and are expected to get in way of each other

[tylerferrara]

Thank you for this readme!
I'll get started on this after I sort out the decentralized line-of-site NESTLab/coms#4