Merge pull request #269 in CASA/casa from hotfix/CAS-10751 to release/5.1.0
* commit '389df936b7bcbade6595f9fe4ac0759acbf92d98':
Cherry pick 55f9467b977 from master to release/5.1.0
Cherry pick 55f9467b977 from master to release/5.1.0
Merge pull request #268 in CASA/casa from bugfix/CAS-10739 to master
* commit '010b6731fa40f8004e05fc0aaa7c662a91208fd6':
add file:// fix to earlier "if", and substitute version path for "stable"
Add missing path to the webbrowser call in init_docs
Prefix parametrized webbrowser call regardless of platform
Fix parametrized webbrowser doc call on Macs