Create smaller supports in problematic areas with established strategies

Completely remove the concept of CompactBridge.

Replace it with Heads having the same back radius as front radius. 

Try to apply the same rules for mini supports as in the route_to_model step.

Increased accuracy of bridge_mesh_intersect shot from support points


Refining mini support integration

src/libslic3r/SLA/SupportTree.cpp

@@ -8,6 +8,7 @@
 #include <libslic3r/SLA/Common.hpp>
 #include <libslic3r/SLA/SpatIndex.hpp>
 #include <libslic3r/SLA/SupportTreeBuilder.hpp>
+#include <libslic3r/SLA/SupportTreeBuildsteps.hpp>
 
 #include <libslic3r/MTUtils.hpp>
 #include <libslic3r/ClipperUtils.hpp>
@@ -103,9 +104,11 @@ SupportTree::UPtr SupportTree::create(const SupportableMesh &sm,
     builder->m_ctl = ctl;
     
     if (sm.cfg.enabled) {
-        builder->build(sm);
+        // Execute takes care about the ground_level
+        SupportTreeBuildsteps::execute(*builder, sm);
         builder->merge_and_cleanup();   // clean metadata, leave only the meshes.
     } else {
+        // If a pad gets added later, it will be in the right Z level
         builder->ground_level = sm.emesh.ground_level();
     }