Added explain functionality.

Uses json format with jsoncpp as a parser. Then show it in a QTreeView.
Shows inclusive/exclusive times like explain.despesz does. Also a similar
coloring scheme as applied.

Ivory.pro

@@ -21,14 +21,19 @@ SOURCES += main.cpp\
     sqlparser.cpp \
     PgsqlConn.cpp \
     queryresultmodel.cpp \
-    sqlhighlighter.cpp
+    sqlhighlighter.cpp \
+    jsoncpp.cpp \
+    queryexplainmodel.cpp \
+    explaintreemodelitem.cpp
 
 HEADERS  += mainwindow.h \
     serverproperties.h \
     sqlparser.h \
     PgsqlConn.h \
     queryresultmodel.h \
-    sqlhighlighter.h
+    sqlhighlighter.h \
+    queryexplainmodel.h \
+    explaintreemodelitem.h
 
 FORMS    += mainwindow.ui \
     serverproperties.ui