Creation of VectorDataset class

(references #41)
Move accessors from GeoVectorValue to VectorDataset

* Adapted LandR classes, now storing a VectorDatastore instead of a GeoVectorValue
* Temporarily deactivated LandR clone() functions
* Temporarily deactivated GeoRaster polygonize() function
* Changed VectorDataset layer and save management, now the constructor no more create a default layer nor save on disk, it becomes the user responsability

(references #41)
Refactoring of the ware signature ID

* Refactored wares signature macros
* Updated observers and sim. functions source codes
* Updated tests datasets
* Updated market tests packages

(closes #75)
Adds and improvements in observers

* Integrated Vtk and Kml observers
* Added CMake macro for installation
* Fixeb bad initialization
* Added tests datasets
* Improved variability in tests
* Updated ware logger tests

(references #51)
(references #52)
(references #53)
Creation of RasterDataset class

(references #41)
Merge remote-tracking branch 'upstream/develop' into refactor-geovalues
Move accessors from GeoRasterValue to RasterDataset

    * Adapted LandR classes, now storing a RasterDatastore instead of a GeoRasterValue
    * Reactivated GeoRaster polygonize() function

(references #41)
openfluid-core no longer depends on geos

(references #41)
LandRGraph and children now deal with Datasets

* LandRGraph and children now can be created from a VectorDataset
* Adding a raster to a LandRGraph can now be done with a RasterDataset
* VectorDataset internal filename is now suffixed with timestamp, allowing creation of many VectorDatasets from the same GeoVectorValue source
* Added Raster/VectorDataset copy constructor

(references #41)
Merge branch 'develop' of https://github.com/OpenFLUID/openfluid into refactor-geovalues
On-Off Switch for building the openfluid-landr library

* Added OPENFLUID_ENABLE_LANDR variable in CMake configuration
  to switch on or switch off the build of the openfluid-landr library
  
(closes #32)
Adaptation of the FindOpenFLUID module for CMake

* Updated default list searched OpenFLUID components, taking
  into account available components
* Fixed CMake configuration for enabled/disabled libraries
* Added FindOpenFLUID test

(references #36)