Version 2.6.0

Possibly incompatible changes

These may be backward incompatible in some cases, as some more-or-less internal APIs have changed.
Please feel free to file issues if you bump into anything strange and we'll try to help!

• Numbers: Refactor decimal handling code and allow bypass of decimal quantization. (@kdeldycke) (PR #538)
• Messages: allow processing files that are in locales unknown to Babel (@akx) (PR #557)
• General: Drop support for EOL Python 2.6 and 3.3 (@hugovk) (PR #546)

Other changes

• CLDR: Use CLDR 33 (@akx) (PR #581)
• Lists: Add support for various list styles other than the default (@akx) (#552)
• Messages: Add new PoFileError exception (@Bedrock02) (PR #532)
• Times: Simplify Linux distro specific explicit timezone setting search (@scop) (PR #528)

Bugfixes

• CLDR: avoid importing alt=narrow currency symbols (@akx) (PR #558)
• CLDR: ignore non-Latin numbering systems (@akx) (PR #579)
• Docs: Fix improper example for date formatting (@PTrottier) (PR #574)
• Tooling: Fix some deprecation warnings (@akx) (PR #580)

Tooling & docs

• Add explicit signatures to some date autofunctions (@xmo-odoo) (PR #554)
• Include license file in the generated wheel package (@jdufresne) (PR #539)
• Python 3.6 invalid escape sequence deprecation fixes (@scop) (PR #528)
• Test and document all supported Python versions (@jdufresne) (PR #540)
• Update copyright header years and authors file (@akx) (PR #559)