Change default stereo panner to equal power balance

The stereo-width panner is not generally useful. In order to
change the azimuth, width has to be reduced, which usually leads
to comb-filter artifacts.

Equal power stereo, also matches the default mono to stereo panner
better than the stereo-width panner.

Last but not least, control surfaces only have an azimuth control
knob, without an easy way to reduce width, this leaves
the panner insensitive.

libs/panners/1in2out/panner_1in2out.cc

@@ -67,7 +67,7 @@ static PanPluginDescriptor _descriptor = {
         "http://ardour.org/plugin/panner_1in2out",
         "http://ardour.org/plugin/panner_1in2out#ui",
         1, 2,
-        10000,
+        20,
         Panner1in2out::factory
 };
 

libs/panners/2in2out/panner_2in2out.cc

@@ -65,7 +65,7 @@ static PanPluginDescriptor _descriptor = {
         "http://ardour.org/plugin/panner_2in2out",
         "http://ardour.org/plugin/panner_2in2out#ui",
         2, 2,
-        10000,
+        20,
         Panner2in2out::factory
 };
 

libs/panners/stereobalance/panner_balance.cc

@@ -64,7 +64,7 @@ static PanPluginDescriptor _descriptor = {
 	"http://ardour.org/plugin/panner_balance",
 	"http://ardour.org/plugin/panner_balance#ui",
 	2, 2,
-	2000,
+	25,
 	Pannerbalance::factory
 };
 

libs/panners/vbap/vbap.cc

@@ -55,7 +55,7 @@ static PanPluginDescriptor _descriptor = {
         "http://ardour.org/plugin/panner_vbap",
         "http://ardour.org/plugin/panner_vbap#ui",
         -1, -1,
-        1000,
+        10,
         VBAPanner::factory
 };