enhancement

[Nemo1166]

New:

• Support loading single-file SD base model (Provide a textbox to insert and use any Stable Diffusion Model #1) (added a link for example).
• Support clip-skip in txt2img generator.
• Added some preset prompts.

Modification:

• Changed the method of loading scheduler (Add more options for schedulers #2), to support more types.

Others:

Possible issues:

• Potential problems that could arise from changing the way the model is loaded were not checked.