Moved everything associated with executing and explaining queries to querytab.

It is now possible to create multiple independent query tabs. However
somethings are currently a bit broken.

pglab.pro

@@ -37,7 +37,9 @@ SOURCES += main.cpp\
     backuprestore.cpp \
     databaseoverviewform.cpp \
     dbschema_database.cpp \
-    querytab.cpp
+    querytab.cpp \
+    stopwatch.cpp \
+    util.cpp
 
 HEADERS  += mainwindow.h \
     serverproperties.h \
@@ -60,7 +62,9 @@ HEADERS  += mainwindow.h \
     expected.h \
     databaseoverviewform.h \
     dbschema_database.h \
-    querytab.h
+    querytab.h \
+    stopwatch.h \
+    util.h
 
 FORMS    += mainwindow.ui \
     serverproperties.ui \