The default config file was changed!

There are two important changes in this update:
- I changed the themis.command.info permission to themis.command.base
- the empty check sections in the config now need {} to mark an empty section, otherwise there will be a warning in the console

Changelog v0.6.1:
- renamed themis.command.info to themis.command.base because I might want to use the info permission for another command in the future
- added an update checker which will notify everyone with the themis.update permission when a new update is detected
- Themis will now check that each of the sections has a (possibly empty) config section and print a warning if that's not the case
- Themis will now ignore detections for the first few seconds after a user joins since there's often lag until the client has loaded everything and fully caught up
- added the ping and tps placeholders to the comments in the default config, changed some of the formatting in the config comments
- some minor code refactoring/cleanup