Have a working model for showing the namespaces in a tree with checkboxes.

The namespaces are currently spit into user and system. Later we might
add recognizing namespaces introduced by specific modules/extensions.

pglab/pglab.pro

@@ -83,7 +83,9 @@ SOURCES += main.cpp\
     PgIndex.cpp \
     PgIndexContainer.cpp \
     PgConstraint.cpp \
-    PgConstraintContainer.cpp
+    PgConstraintContainer.cpp \
+    NamespaceFilterWidget.cpp \
+    NamespaceItemModel.cpp
 
 HEADERS  += \
     QueryResultModel.h \
@@ -138,7 +140,9 @@ HEADERS  += \
     PgIndex.h \
     PgIndexContainer.h \
     PgConstraint.h \
-    PgConstraintContainer.h
+    PgConstraintContainer.h \
+    NamespaceFilterWidget.h \
+    NamespaceItemModel.h
 
 FORMS    += mainwindow.ui \
     DatabaseWindow.ui \
@@ -150,7 +154,8 @@ FORMS    += mainwindow.ui \
     BackupDialog.ui \
     ServerWindow.ui \
     ProcessStdioWidget.ui \
-    TablesPage.ui
+    TablesPage.ui \
+    NamespaceFilterWidget.ui
 
 RESOURCES += \
     resources.qrc