[Setup] Use instance name in default data path

[jack1142]

Type

• Bugfix
• Enhancement
• New feature

Description of the changes

• instance names can now only include characters A-z, numbers, underscores, and hyphens - this isn't strictly required - we could have checks for invalid characters in Windows folder names, but supporting all sorts of characters could possibly be troublesome in other cases too
• redbot-setup will now use instance name in default data path to avoid creating second instance with same data path - the new datapath should typically (everything before Red-DiscordBot is dependent on what appdirs gives us as it was before) be as follows:
  • Mac OS X: ~/Library/Application Support/Red-DiscordBot/data/<instance_name>
  • Unix: ~/.local/share/Red-DiscordBot/data/<instance_name>
  • Win: C:\Users\<username>\AppData\Local\Red-DiscordBot\Red-DiscordBot\data\<instance_name>
• redbot-setup and redbot --edit should now gracefully handle invalid folder names for data path
• few small changes in ``redbot --edit` (consistency)