Allow loading float values from rasters to PolygonGraph

* Modified code based on GDALFPolygonize method 
* Updated tests
Fix of non-critical misspellings in landr library

* Fixed mispellings in Exceptions
* Fixed bad english translations
Merge branch 'develop' into develop-qt
Merge branch 'develop-qt' of https://github.com/chataignerm/openfluid into chataignerm-develop-qt