added theme system, makes it easier to add more color schemes

src/generics.go

@@ -10,3 +10,10 @@ func Contains[E comparable](s []E, v E) bool {
 
 	return false
 }
+
+func Exists[K comparable, V any](m map[K]V, v K) bool {
+	if _, ok := m[v]; ok {
+		return true
+	}
+	return false
+}