o.c.archive: Added new interface for archive requests. Changed
trendplotter.
o.c.application.xmlrpc.server: Bug fixed in class ValuesCommand to
handle time difference <= 0
o.c.archive.request.*: Added new implementation for archive record.
Added new method to request interface to get all supported request
types.
o.c.archive.request.xmlrpc: Removed unnecessary method.
Merge branch 'rel15x' into develop-rel15x