Generic slider (#14)

* good coverage

* merged classes

* working cross platform

* range slider tests working too

* many more fixes and unification

* type

* reorg

* working labels, better typing

* tests

* legacy compat

* update envlist

* skip mouse press not on mac

* fix getStyleOption

* fix again

* skip hover

* remove print

* add module docstring

examples/demo_widget.py

@@ -112,10 +112,10 @@ if __name__ == "__main__":
     app = QtW.QApplication([])
     demo = DemoWidget()
 
-    if "-x" in sys.argv:
-        app.exec_()
-    else:
+    if "-snap" in sys.argv:
         import platform
 
         QtW.QApplication.processEvents()
         demo.grab().save(str(dest / f"demo_{platform.system().lower()}.png"))
+    else:
+        app.exec_()