removed obsolete files
updated MultiArrayView documentation
started documenting GridGraph
updated credits and changelog
finished documentation of GridGraph
minor improvements of GridGraph documentation
added relational operators for autodiff::DualVector
support automatic differentiation of BSplines
fixed macro VIGRA_DUALVECTOR_RELATIONAL_OPERATORS
minor documentation fixes
changed shared library version format (patch by Hans Meine)
fixed cmake warning
remove now-unused cmake var. definition

(see initial patch in issue #163)
silenced new gcc warnings
compatibility fixes for Visual Studio 2013
cmake: improved search for boost libraries
fixed typo in tutorial
removed invalid using declaration
removed debug output in labelvolume.hxx
ignore potential python3 installations