#59: \Panza\Library\IssueRepository search() returns \Panza\Library\Issue[] (instead of array<string>)
#59: \Panza\Library\Issue getLinks() -> the same change as search()
#59: IssuePoller uses new search() interface
#59: LinkedIssuesNotifier uses new getLinks() interface
#59: dependency IssueRepository removed for LinkedIssuesNotifier.
Merge pull request #60 from panza-official/issue_59

#59: related to issue