Tricks rework

[williambl]

• Replaces hardcoded trick creation from string with trick creation from slash command arguments
• Re-adds arguments for tricks
• Re-adds dedicated per-trick commands
• Makes addtrick command not hardcoded just for string and embed trick types, so that new trick types will work
• Adds edittrick command for editing/replacing tricks
• Adds some util functions to make getting slash commands in a null-safe way more easy

Still needs thorough testing.

[KiriCattus]

Good to be merged here @williambl ? :)

[williambl]

One thing before merge