Bugfixes and improvements

Bugfix: OracleSqlParser - JOIN clause correctly resolved when join type
seems as table alias, e. g., SELECT NULL FROM SELECTION LEFT JOIN
RESPONDENTBUCKET RB ON SELECTION.RESPONDENTBUCKET_ID =
RB.RESPONDENTBUCKET_ID
Bugfix: StatementDescriptionNode.GetPathFilterAncestor - filter now
applied also for nested nodes
Improved: OracleCodeCompletionProvider - outside FROM clause suggest
only tables (aliases) already present in the FROM clause
Improved: OracleSnippetProvider - A snippet can specify list of
terminals and the snippet is suggested only if at least one of the
supported terminals is valid next terminal when typing statement
Added: new unit tests
Refactoring: OracleSemanticValidatorTest methods renamed to meaningful
names