This fixes PR 43165.
Major changes:
- added and documented |[xy]bar legend| styles and |[xy]bar interval
legend| styles
- renamed 'every mesh legend' to 'mesh legend' for consistency
- improved 'mesh legend' (rescaled and reshiftet it a bit)
- Imported all patches to PGF written by Christian Feuersaenger.
- added |tiny| style
- numerous bug fixes
See ChangeLog in tex-pgfplots-doc for the complete list of changes.
