translation-tool.pl supports backslash

 - When backslash was used in translation then generated template for translation was broken. Only first line was copied, rest was missing and because of \ and next key was also not properly processed.
 - Adds lib for reading properties files instead of own implementation

### Proposed changelog entries

### Submitter checklist

- [ ] JIRA issue is well described
- [ ] Changelog entry appropriate for the audience affected by the change (users or developer, depending on the change).
- [ ] Appropriate autotests or explanation to why this change has no tests
- [ ] For dependency updates: links to external changelogs and, if possible, full diffs

### Desired reviewers
@batmat