Organic Supports improvements:

Added support_tree_branch_distance parameter to UI
Fixed error in calculation of placeable areas, which made some trees to cut through an object.
Locked the tree tips against smoothing of their centerline path.
Reduced density of tips with zero interface layers (see continuous_tips).
Reduced default support_tree_top_rate to 15%
Refactored placement of interfaces for readability.

src/libslic3r/PrintConfig.cpp

@@ -2910,6 +2910,18 @@ void PrintConfigDef::init_fff_params()
     def->mode = comAdvanced;
     def->set_default_value(new ConfigOptionFloat(5));
 
+    // Tree Support Branch Distance
+    // How far apart the branches need to be when they touch the model. Making this distance small will cause 
+    // the tree support to touch the model at more points, causing better overhang but making support harder to remove.
+    def = this->add("support_tree_branch_distance", coFloat);
+    def->label = L("Branch Distance");
+    def->category = L("Support material");
+    def->tooltip = L("How far apart the branches need to be when they touch the model. "
+                     "Making this distance small will cause the tree support to touch the model at more points, "
+                     "causing better overhang but making support harder to remove.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(1.));
+
     def = this->add("support_tree_top_rate", coPercent);
     def->label = L("Branch Density");
     def->category = L("Support material");
@@ -2921,7 +2933,7 @@ void PrintConfigDef::init_fff_params()
     def->min = 5;
     def->max_literal = 35;
     def->mode = comAdvanced;
-    def->set_default_value(new ConfigOptionPercent(30));
+    def->set_default_value(new ConfigOptionPercent(15));
 
     def = this->add("temperature", coInts);
     def->label = L("Other layers");