• Remove vague mention of outdated tex packages (first because it was written more than 10 years ago so packages too old for backend_pgf compatibility are unlikely to be seen nowadays, and second because if we don't actually provide compatibility bounds such a statement is not particularly useful).
• Fix consistency between xetex/xelatex, and also for capitalization.
• Remove an unnecessary encoding step in PdfPages by directly formatting bytes.

PR summary

PR checklist

• "closes #0000" is in the body of the PR description tolink the related issue
• new and changed code istested
• Plotting related features are demonstrated in anexample
• New Features andAPI Changes are noted with adirective and release note
• Documentation complies withgeneral anddocstring guidelines