* llm prompt --save option support, closes#830
* Fix for templates with just a system prompt, closes#844
* Tests for options from template, refs #830
* Test and bug fix for --save with options, refs #830
* Docs for template options support, refs #830
* Don't hang on stdin if llm -t template-with-schema
* Docs on using schemas with templates
* Schema in template YAML file example
* Test for --save with --schema
Refs #778
This allows default values to be filled for templates.
For example:
```yaml
prompt: Summarize this text in the voice of $voice
defaults:
voice: GlaDOS
```