Add support for building and user as "groups"

[Feilner]

Gravo supports already groups but the other two group types named building and user where missing.

Also do a better hierarchical order. Until now only the direct parent is shown in braces after the title. In a hierarchical structure with several levels that's not sufficient. because e.g. in the following structure within Volkszähler

my building                                  (type building)
|- 1st floor                                 (type group)
|    |- bathroom                             (type group)
|    |    |- temperature                     (type sensor)
|    |    \- humidity                        (type sensor)
|    \- sleeping room                        (type group)
|         |- temperature                     (type sensor)
|         \- humidity                        (type sensor)
\- 2nd floor                                 (type group)
     \- bathroom                             (type group)
          |- temperature                     (type sensor)
          \- humidity                        (type sensor)

There where twice identical entries: temperature (bathroom) humidity (bathroom)

Therefore I propose a folder like structure where this entries become to: my building\1st floor\bathroom\temperature my building\2nd floor\bathroom\temperature

[andig]

I'm not quite sure what this does- could you show before/ after output?