Commands

- Implements #616.
- Adds the new invasion types to /invade (snow legion & pirates)
- Changes Log methods to format object[] instead of string[].
- Removes specific boss spawning commands. Wall of Flesh edge-case added into /spawnmob.
- Removes /debugreg (now useless).
- Removes /star.
- Merges /killprojectile and /clearitems into one command, /clear.
- Merges /stophardmode and /starthardmode into one toggle command, /hardmode.