Add extra options to theme-preview.sh for config

[Rycieos]

The original intent for theme-preview.sh was to have a reference for a static output of a theme. So all runs of the tool for a specific theme would always show the same output.

But a different, completely valid use is to see how a theme would look with your config, or to see how changing your config might change how a theme looks.

Add optional arguments that will allow for loading the user config, input files, or to return to the original functionality of locking the COLUMNS to a set value.

There is still no way to control the mocked data, and there might still be some weird quirks with the imbedded config in the tool conflicting with user config.

Fix the minimal theme using the wrong PS1 variable.
Fix Zsh crash in unfold theme.

Fixes #800

[nojhan]

Awesome, that's going to be useful.

I tested with several themes and presets and it works well, except for the minimal theme, which ends on missing LP_PS1_PREFIX.

[Rycieos]

it works well, except for the minimal theme, which ends on missing LP_PS1_PREFIX.

So the minimal theme is actually not a theme, but instead a "default theme template" (aka a Liquid Prompt v1 theme). To use such a template, you need to set LP_PS1_FILE to its path.

Likely it should not have been under themes/, since that is just confusing. Maybe we move it to a templates/ directory?

It does leave the UX lacking though. You can load a template like this with an inline config file:

./tools/theme-preview.sh default --config-file <(echo LP_PS1_FILE=themes/minimal/minimal.ps1)

But maybe we add an argument, --template-file, that will do that substitution for you?

[nojhan]

But maybe we add an argument, --template-file, that will do that substitution for you?

I guess that would be the clearest option for a naive user, indeed.

[Rycieos]

This is ready for review. The failed docs lint is because I moved the minimal.ps1 file, and the docs are looking for the new location on the master branch.

[nojhan]

Looks good, just two minor (and optional) questions.