tracker/pt, options: fix threshold slider

It's only the tie_setting(slider_value, QSlider) that
has race-free slider updates. Needed to update the
threshold slider representation.

Remove the tie_setting(int, QSlider) overload since it
doesn't have the logic.

Add a migration.

Add base_value::notify() for use-cases like the
checkbox updating the label.

1 files changed, 2 insertions, 0 deletions

diff --git a/options/base-value.hpp b/options/base-value.hpp
index 5106908d..dfb22670 100644
--- a/options/base-value.hpp
+++ b/options/base-value.hpp
@@ -41,6 +41,8 @@ public:
         return static_cast<signal_sig<t>>(&base_value::valueChanged);
     }
 
+    void notify() const;
+
 signals:
     OPENTRACK_DEFINE_SIGNAL(double);
     OPENTRACK_DEFINE_SIGNAL(float);