[SEC] installer: make locking the installer the default option; add warning to encourage use of secure login; replace links with posts (was supposed to be in r50345)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@50353 b456876b-0849-0410-b77d-98878d47e9d5
[MRG] Automatic merge, branches/12.x 50351 to 50353
Conflicts in templates/tiki-install.tpl fixed manually

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@50354 b456876b-0849-0410-b77d-98878d47e9d5
installer: minor formatting fixes after last automerge.

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@50358 b456876b-0849-0410-b77d-98878d47e9d5