o 2.59.5

• Don't call os.Getenv several times. Call os.Environ once and then cache the variables. This is handled automatically by the github.com/xyproto/env/v2 package. There is a tiny performance improvement for o because of this.
• Add a Makefile target for building with the trace build tag.
• Set the default ChatGPT temperature to 0, for generating code and to 0.8 for generating other text.
• In addition to ! for filetypes other than Markdown, only use Write and write as "trigger words" for starting to generate code or text with ChatGPT (and only if the CHATGPT_API_KEY is set).
• Update dependencies.
• Update documentation.