fix #2322: GPX imported caches not marked as owned

The "isOwner()" property (previously named "isOwn()") is now
synthesized by comparing the username with the cache owner name.
Merge branch 'issue-2322' into upstream

Conflicts:
	main/src/cgeo/geocaching/connector/IConnector.java
	main/src/cgeo/geocaching/connector/gc/GCParser.java
	main/src/cgeo/geocaching/maps/CGeoMap.java
Merge branch 'master' of github.com:cgeo/c-geo-opensource into upstream