Make it possible to also interpret Time intervals delivered as Concepts

[l00mi]

The goal of this task would be to understand apart of the time dimensions which come with the classical units (year, weeks, days) to also understand time intervals with a 'time:hasBegining' and `time:hasEnd'.

This is for the WSL use case and more details will follow.

[IsabelMeraner]

Our use case includes so-called "inventories", spanning over multiples years, eg. NFI4.

<http://www.wsl.ch/ldlfi/Inventory#450> a nfi:Inventory, time:TemporalEntity ;
    schema:description """Auswertung der Inventur im Nafidas"""@de ;
    schema:name "NFI4", "LFI4"@de, "NFI4"@en, "IFN4"@fr, "IFN4"@it ;
    nfi:inventoryRegion <http://www.wsl.ch/ldlfi/InventoryRegion#1> ;
    nfi:inventoryType <http://www.wsl.ch/ldlfi/InventoryType#1> ;
    time:after <http://www.wsl.ch/ldlfi/Inventory#350> ;
    time:hasBeginning "2009-08-10T00:00:00"^^xsd:dateTime ;
    time:hasEnd "2017-11-03T00:00:00"^^xsd:dateTime .

Single observations reference the inventories as follows:

<http://www.wsl.ch/ldlfi/Observation/366-1001-None-None_Geswald34_350_3_11> a cube:Observation ;
    nfi:forestArea 8e+02 ;
    nfi:standardErrorForestArea 5e+01 ;
    ...
    nfi:inventory <http://www.wsl.ch/ldlfi/Inventory#350> .

current version of shape.ttl:

    sh:property [ 
           sh:path nfi:inventory 
            a cube:KeyDimension ;
            schema:name "Schweizerisches Landesforstinventar"@de,
                "Swiss National Forest Inventory"@en,
                "Inventaire forestier national suisse"@fr,
                "Inventario Forestale Nazionale Svizzero"@it ;
            qudt:scaleType qudt:NominalScale ;
            sh:nodeKind sh:IRI ;
            sh:in (<http://www.wsl.ch/ldlfi/Inventory#150> <http://www.wsl.ch/ldlfi/Inventory#250> 
                     <http://www.wsl.ch/ldlfi/Inventory#350> <http://www.wsl.ch/ldlfi/Inventory#450>) ;
    ],