Enabled PETSc 3.5
Specify full path in #include.

This is required for an upcoming application.
It was already discussed in #89 and will come up
with more changes as the application grows. So
step by step all #includes will have the full
paths prepended.
[IO] Clarify which mesh file was read.
[ML] Specify full path for some includes.
Consistent copyright year 2012-2014.
Changed if-condition for PETSc version according to the suggestion by Nori
use boost::optional as a return value of getMeshNodeIDForPoint()
add a general searching function for any geometric types in MeshNodeSearcher
Merge pull request #452 from endJunction/Cleanup

Cleanup
[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
adjusted LayeredVolume-interface to take raster files from bottom to top
Merge pull request #450 from wenqing/forPETSc35

Enabled PETSc 3.5
changed static methods in MeshLayerMapper to non-static
add explicit and assignment operator to DenseMatrix