Added multi-model selection and bulk sub_* function rename features and merged with Vulchat

[warsang]

Hi!

I forked this intially for personal use but decided I would share some of the changes I made (I mostly wanted model selection and being able to bulk rename functions).
Beware, a few edits may be needed as I couldn't 100% test everything as I ended up running out of tokens but the bulk of the code works and I fixed whatever was broken while I still had tokens.

Features include:

• Model selection (I use a tkinter pop-up; there may be an ida-only api way to do it but this was just easy to implement)
• Merge with Vulchat ( https://github.com/ke0z/VulChatGPT ): Vulchat is still using dali-003 . There will probably be better perf/results when leveraging these new models and gpt 3.5/4.
  I couldn't test the two below because I ran out of token so a few edits may be needed to get these to work 100%
• Rename function: Similar to rename_variables but will rename the function
• Rename all sub_: This will rename all sub_ functions that are less than 800 characters long (we can probably bump this up but I needed threshold). It has the potential to make a lot of api calls so a warning before using it may be desirable.

[JusticeRage]

Wow, thanks a lot for your PR! I'll look into the code and merge as soon as I get a chance!