SDXL sketch support, prompt length changes, and better forging

- Added support for sdxl sketch.
- Added validation for prompt lengths in style creator.
- Added more human readable errors to the application.
- Improved quality of forges by auto-increasing density when selected area is considerably smaller than the wider canvas.
- Fixed an issue with redo shortcut (ctrl+shift+z)
- Fixed issues with dark theme blending in with light theme.
- Fixed an issue with the styles page not showing posted images correctly.
- Fixed an issue when training prompts could not be easily read or modified.



