A few additions and fixes

[FrostBird347]

Fixed issues #59 and #46. Added an option to:

• Change the delay between each split message
• Add the channel's slowmode length to the delay above
• Limit the maximum number of split messages sent at once
• Determine what's done with any of the extra messages that won't be sent due to the split message limit

Also added 'defaultValue' attribute to each slider option, set to the actual default values.

[QbDesu]

Lovely, thanks a lot. I'll try to get around to reviewing it in more detail tomorrow. I will probably merge it and change things I want changed myself to make the process easier.

[QbDesu]

The reason why I didn't get around to merging this yet is because there is a lot of things going on in terms of development on BetterDiscord itself at the moment + the recent discord update that broke a ton of plugins.