Fix missing public keywords

include/Gedeng/NavMesh.h

@@ -12,6 +12,7 @@ namespace Gedeng {
 // 4. Get a path between the desired points via NavMesh::get_path
 // 5. Position an entity along this path via Path::get_interpolated_position
 class NavMesh {
+  public:
     // Build the NavMesh from all collider geometry in the given node and all
     // its children.
     void create_from_nodes(const Node &root);

include/Gedeng/Node.h

@@ -5,6 +5,7 @@
 namespace Gedeng {
 
 class Node {
+  public:
     // Add the given node as a child of this node.
     void add_child(const Node &node);
 

include/Gedeng/NodeSystem.h

@@ -5,6 +5,7 @@
 namespace Gedeng {
 
 class NodeSystem {
+  public:
     // Load a node with all its children from a node definition file (`.gnd`) on
     // disk.
     static Node load_nodes_from_disk(const String &path);

include/Gedeng/Path.h

@@ -4,6 +4,7 @@
 namespace Gedeng {
 
 class Path {
+  public:
     // Return a Vector3 on the path. `t` should be between 0 (path begin) and 1
     // (path end).
     Vector3 get_interpolated_position(float t) const;