Enabled PETSc 3.5
Changed if-condition for PETSc version according to the suggestion by Nori
[bugfix] fixed issue where raster to mesh conversion would fail if all all intensity values were negative
Merge branch 'master' of https://github.com/ufz/ogs
Replace BaseLib::number2str with std::to_string.

Also remove the header StringTools.h everywhere.
Add a previously missing sstream include in DateTools.cpp.
[GeoLib] Another version for GEOObjects::getGeoObjects().

The commit is a preparation to access GeoObject objects via the geometry
name and the object name (patch name).
Merge pull request #448 from TomFischer/GeoLibGetGeoObjectsByName

[GeoLib] Another version for GEOObjects::getGeoObjects().
Merge pull request #456 from endJunction/StdToString

Replace BaseLib::number2str with std::to_string.
Added one more condition for PETSc versions
Merge pull request #450 from wenqing/forPETSc35

Enabled PETSc 3.5
Remove/Comment ProjectData related changes.

The ProcessInfo and the boundary conditions are changing.
The FEMCondition's are depricated.

We change to variable-centred initial and boundary
conditions.
Remove FEMCondition and its BoostXml reader.
Remove ProcessInfo class as well.
Implementation of IC/BC and ProcessVariable.
Empty GroundwaterFlowProcess and its Base classes.
[PL] Add ProcessLib to CMake files.
Add ProcessLib to doxygen inputs.
[PL] Add virtual initialize().
[PL] Add number of node variables.

Element variables are not yet used.
[PL] Add destructor for GroundwaterFlowProcess.