style: unify identifier naming per updated conventions

Automated with clang-tidy readability-identifier-naming (config added to
.clang-tidy) plus scripted passes, per the updated rules now documented
in CONTRIBUTING.md:

- types (class/struct/enum/alias/template params): PascalCase
- functions, variables, members: snake_case (incl. rational -> Rational)
- private/protected members: trailing underscore; static member
  variables likewise (instance_, available_themes_)
- constants and enum values: snake_case (kLinear -> k_linear,
  F32P -> f32p); ALL_CAPS reserved for macros
- macros: OAK_ prefix (OLIVE_ADD_TEST/OLIVE_ASSERT/OLIVE_CONFIG ->
  OAK_ADD_TEST/OAK_ASSERT/OAK_CONFIG, GL_PREAMBLE -> OAK_GL_PREAMBLE,
  include guards -> OAK_*)
- file names: all lowercase (Current/Plugin/OliveHost/OliveClip/
  OlivePluginInstance -> current/plugin/olivehost/oliveclip/
  oliveplugininstance)
- getters share the member name sans underscore, setters set_foo()
- Qt and third-party (OpenFX) virtual overrides and framework callbacks
  keep their original names (exempt in .clang-tidy)

Manual follow-ups required where automation could not reach:
- string-based QMetaObject/SIGNAL/SLOT references updated to renamed
  methods (AddTask, CreatedFile, DeleteSpecificFile, moveSelectionUp, ...)
- macro bodies referencing renamed methods (OLIVE_CONFIG,
  NODE_DEFAULT_DESTRUCTOR, MANAGEDDISPLAYWIDGET_*)
- self-shadowing locals renamed where signals/methods became same-named
  (size_changed, worker_count, selected_items, import param, filters)
- third_party OFX member/namespace usages restored (OFX::Host::*,
  _created, _clipPrefsDirty, createInstance, clearPersistentMessage)
- STL protocol aliases restored (const_iterator) with .clang-tidy
  ignore rules; qHash overloads restored

Full build and test suite pass: ctest 4/4, ~1960 gtest cases green.

app/panel/project/project.h

@@ -19,8 +19,8 @@
 
 ***/
 
-#ifndef PROJECT_PANEL_H
-#define PROJECT_PANEL_H
+#ifndef OAK_PROJECT_PANEL_H
+#define OAK_PROJECT_PANEL_H
 
 #include "footagemanagementpanel.h"
 #include "node/project.h"
@@ -45,49 +45,49 @@ public:
 
 	void set_root(Folder *item);
 
-	QVector<Node *> SelectedItems() const;
+	QVector<Node *> selected_items() const;
 
-	Folder *GetSelectedFolder() const;
+	Folder *get_selected_folder() const;
 
-	virtual QVector<ViewerOutput *> GetSelectedFootage() const override;
+	virtual QVector<ViewerOutput *> get_selected_footage() const override;
 
 	ProjectViewModel *model() const;
 
-	bool SelectItem(Node *n, bool deselect_all_first = true)
+	bool select_item(Node *n, bool deselect_all_first = true)
 	{
-		return explorer_->SelectItem(n, deselect_all_first);
+		return explorer_->select_item(n, deselect_all_first);
 	}
 
-	virtual void SelectAll() override;
-	virtual void DeselectAll() override;
+	virtual void select_all() override;
+	virtual void deselect_all() override;
 
-	virtual void DeleteSelected() override;
+	virtual void delete_selected() override;
 
-	virtual void RenameSelected() override;
+	virtual void rename_selected() override;
 
 public slots:
-	void Edit(Node *item);
+	void edit(Node *item);
 
 signals:
-	void ProjectNameChanged();
+	void project_name_changed();
 
-	void SelectionChanged(const QVector<Node *> &selected);
+	void selection_changed(const QVector<Node *> &selected);
 
 private:
-	virtual void Retranslate() override;
+	virtual void retranslate() override;
 
 	ProjectExplorer *explorer_;
 
 private slots:
-	void ItemDoubleClickSlot(Node *item);
+	void item_double_click_slot(Node *item);
 
-	void ShowNewMenu();
+	void show_new_menu();
 
-	void UpdateSubtitle();
+	void update_subtitle();
 
-	void SaveConnectedProject();
+	void save_connected_project();
 };
 
 }
 
-#endif // PROJECT_PANEL_H
+#endif // OAK_PROJECT_PANEL_H