Fixed CORE-4137 - Wrong metadata output script generate by isql / CHARACTER SETISO8859_1 sintaxe error.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_5_Release@58286 65644016-39b1-43b1-bf79-96bc8fe82c15
Backported CORE-3874: Computed column appears in non-existant rows of left join.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_5_Release@58288 65644016-39b1-43b1-bf79-96bc8fe82c15
Better protection against AST delivery during detaching.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_5_Release@58291 65644016-39b1-43b1-bf79-96bc8fe82c15
Better protection against AST delivery during detaching. Second attempt combined with cleanup.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_5_Release@58294 65644016-39b1-43b1-bf79-96bc8fe82c15