made save style button not die when you cancel

Tag/Option Parsing in Prompts From File

add --ckpt-cache option for faster model switching

- Check the actually used `$python_cmd` and `$GIT` executables instead
  of the hardcoded ones
- Fix typo in comment

This is only necessary when you have to train,
and compiling model produces warning.

Fix XY-plot steps if highres fix is enabled

Raise an assertion error if no training images have been found.

Allow change set --index-url for pip.