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/widget/handmovableview/handmovableview.h

@@ -19,8 +19,8 @@
 
 ***/
 
-#ifndef HANDMOVABLEVIEW_H
-#define HANDMOVABLEVIEW_H
+#ifndef OAK_HANDMOVABLEVIEW_H
+#define OAK_HANDMOVABLEVIEW_H
 
 #include <QGraphicsView>
 #include <QMenu>
@@ -37,7 +37,7 @@ public:
 
 	static bool WheelEventIsAZoomEvent(QWheelEvent *event);
 
-	static qreal GetScrollZoomMultiplier(QWheelEvent *event);
+	static qreal get_scroll_zoom_multiplier(QWheelEvent *event);
 
 	virtual void CatchUpScrollEvent()
 	{
@@ -49,19 +49,19 @@ protected:
 		Q_UNUSED(tool)
 	}
 
-	bool HandPress(QMouseEvent *event);
-	bool HandMove(QMouseEvent *event);
-	bool HandRelease(QMouseEvent *event);
+	bool hand_press(QMouseEvent *event);
+	bool hand_move(QMouseEvent *event);
+	bool hand_release(QMouseEvent *event);
 
-	void SetDefaultDragMode(DragMode mode);
-	const DragMode &GetDefaultDragMode() const;
+	void set_default_drag_mode(DragMode mode);
+	const DragMode &get_default_drag_mode() const;
 
 	virtual void wheelEvent(QWheelEvent *event) override;
 
-	virtual void ZoomIntoCursorPosition(QWheelEvent *event, double multiplier,
+	virtual void zoom_into_cursor_position(QWheelEvent *event, double multiplier,
 										const QPointF &cursor_pos);
 
-	void SetIsTimelineAxes(bool e)
+	void set_is_timeline_axes(bool e)
 	{
 		is_timeline_axes_ = e;
 	}
@@ -77,9 +77,9 @@ private:
 	bool is_timeline_axes_;
 
 private slots:
-	void ApplicationToolChanged(Tool::Item tool);
+	void application_tool_changed(Tool::Item tool);
 };
 
 }
 
-#endif // HANDMOVABLEVIEW_H
+#endif // OAK_HANDMOVABLEVIEW_H