Dark mode support

Centralized all colors, tweaked application paletter in darkmode to make it darker.

pglab/util/Colors.h

@@ -0,0 +1,48 @@
+#include <QColor>
+#include "Pgsql_oids.h"
+
+#pragma once
+
+bool isDarkMode();
+
+struct ColorTheme
+{
+    QColor defaultTextColor;
+
+    QColor gutterBackground;
+    QColor lineNumber;
+    QColor currentLine;
+    QColor errorLine;
+
+    QColor keyword;
+    QColor comment;
+    QColor quotedString;
+    QColor quotedIdentifier;
+    QColor type;
+    QColor parameter;
+
+    QColor gigaBytes;
+    QColor megaBytes;
+    QColor kiloBytes;
+    QColor bytes;
+
+    QColor booleanTrue;
+    QColor booleanFalse;
+
+    QColor integerColor;
+    QColor floatColor;
+    QColor numericColor;
+    QColor nullColor;
+
+    QColor numericTypeColor;
+    QColor dateTimeTypeColor;
+    QColor stringTypeColor;
+
+
+    QColor GetColorForType(Oid oid) const;
+
+};
+
+const ColorTheme& GetColorTheme();
+
+void InitApplicationPalette();