Fix ircbot

[Matouš Skála]

With the introduction of QTable, general and dna commands of ircbot stopped working. It is probably unnecessary to introduce the qtable command, but at least the following should be done:

• Add tree field to VPSState and properly update it when creating a child QTable (see the original implementation for DNA)
• Use qtable.self_state to return provider, option, and tree in the general command
• Remove the dna command

[Rafał Pytel]

About irc, I remember we were discussing on one of the meetings in December that we plan to get rid of irc communication. It is worth checking on our tomorrow's meeting to clarify that.

[Matouš Skála]

Without IRC, there would be currently no way to track the state of the network, so we need to keep it for debugging purposes, at least until another way of communication is introduced. Moreover, there are some visualization tools (in the tools directory) dependent on it.