ENH: udpate version number to 4.4.0

DOC: update release notes

DOC: update release dates

ENH: update release notes with index conventions

--HG--
extra : rebase_source : 610428f0f199e724209b6ee20c5e15a399f601c4

ENH: update release notes

ENH: clarify comment for DefaultConvertPixelTraits< complex > and fix…

… style

COMP: revert tagging 3.20.0 to include compilation patch

ENH: update release notes

Update release notes and the version number

ENH: update date in release notes