graphviz 2.26.0 and higher, layout engine detection fix (linux)

[Matthias]

Fixup for graphviz 2.26.0+ Layout Engine Detection, see ​http://trac-hacks.org/wiki/ProjectPlanPlugin/DotCompatibility

I dont know wether this is a derivate ₁/graphviz Problem ₂. From graphviz dot Manpage: "-Klayout override the default layout engine implied by the command name.". This does not work in projectplanplugin/0.11/trunk/projectplan/dotrender.py@7634#L103​ (may caused by non-shell execution), neither the implication nor the -K option. After some Tests it seems, the -K is explicit hard-coded: "dot dot ..." instead of "dot -Kdot ..." works and "dot ..." returns the same Error as "dot -K ...".

For now a (temporary/selectable) workaround would be nice.

1. _{Tree Stamp: Wed, 24 Feb 2010 07:00:01 +0000}
2. _{couldn't find neither bug reports for 2.6 nor 2.26 (​http://www.graphviz.org/bugs/buglist.html)}

[Matthias]

(In [7722]) dot 2.26.0+ K cmdline fix selectable in admin panel, improved error log link, closes #6728