Set gomill version number to 0.8.3; release dates

Set gomill version number to 0.8.2; release dates

Set gomill version number to 0.8.1; release dates

Set gomill version number to 0.8; release dates

Set gomill version number to 0.7.4; release dates

Set gomill version number to 0.7.3; release dates

sgf.rst: fix a link nitpick

readme.txt: bump date

changes.rst: today's date for gomill 0.7 release

Doc that --user isntall puts ringmaster into ~/.local/bin