Resolve relative links only in namespaces with subpages enabled.
Enable 'title' and 'subpages' options in parserTests.js.

Store which namespaces have subpages enabled in
WikiConfig.namespacesWithSubpages. When a namespace doesn't have
subpages enabled, don't resolve relative links.

Parser tests that now pass:
- Magic Word: {{FULLPAGENAME}}
- Magic Word: {{PAGENAME}} with metacharacters
- Magic Word: {{PAGENAME}} with metacharacters (bug 26781)
- Subpage link
- Disabled subpages
- Parents of subpages, one level up
- Parents of subpages, two levels up

Bug: 47136
Change-Id: I055c451685d98f3951472677e745b9e077970c21
Merge "Resolve relative links only in namespaces with subpages enabled. Enable 'title' and 'subpages' options in parserTests.js."