nodeGraph and updated info()

I've added the node graph functionality into the katRun object, as katRun.nodeGraph(). Give it a try, and if you like it, I'd be happy to see it merged :) Also, I slightly updated the katRun.info() function so that it now also displays the x location of minima/maxima -- might need further testing.

Warning: I had to remove the .gitlab-ci.yml file so that the project wouldn't show errors on gitlab, but of course you would want to keep this file. Not sure how to exclude that change from a merge request, though :-(

pykat/__init__.py

@@ -8,6 +8,7 @@ __version__ = "1.0.8"
 # This flag is used to switch on the gui features in pkat at import time
 USE_GUI = False
 HAS_OPTIVIS = False
+HAS_GRAPHVIZ = False
 
 import imp
 
@@ -17,6 +18,13 @@ try:
 except ImportError:
 	HAS_OPTIVIS = False
 
+try:
+    imp.find_module('pygraphviz')
+    HAS_GRAPHVIZ = True
+except ImportError:
+    HAS_GRAPHVIZ = False
+
+
 import pykat.exceptions as pkex
 
 NoGUIException = pkex.BasePyKatException("No PyQt4 module was found so cannot open a GUI")