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/node/inputdragger.h

@@ -19,8 +19,8 @@
 
 ***/
 
-#ifndef NODEINPUTDRAGGER_H
-#define NODEINPUTDRAGGER_H
+#ifndef OAK_NODEINPUTDRAGGER_H
+#define OAK_NODEINPUTDRAGGER_H
 
 #include "node/keyframe.h"
 #include "node/param.h"
@@ -33,31 +33,31 @@ class NodeInputDragger {
 public:
 	NodeInputDragger();
 
-	bool IsStarted() const;
+	bool is_started() const;
 
-	void Start(const NodeKeyframeTrackReference &input, const rational &time,
+	void start(const NodeKeyframeTrackReference &input, const Rational &time,
 			   bool create_key_on_all_tracks = true);
 
-	void Drag(QVariant value);
+	void drag(QVariant value);
 
-	void End(MultiUndoCommand *command);
+	void end(MultiUndoCommand *command);
 
-	static bool IsInputBeingDragged()
+	static bool is_input_being_dragged()
 	{
 		return input_being_dragged;
 	}
 
-	const QVariant &GetStartValue() const
+	const QVariant &get_start_value() const
 	{
 		return start_value_;
 	}
 
-	const NodeKeyframeTrackReference &GetInput() const
+	const NodeKeyframeTrackReference &get_input() const
 	{
 		return input_;
 	}
 
-	const rational &GetTime() const
+	const Rational &get_time() const
 	{
 		return time_;
 	}
@@ -65,7 +65,7 @@ public:
 private:
 	NodeKeyframeTrackReference input_;
 
-	rational time_;
+	Rational time_;
 
 	QVariant start_value_;
 
@@ -79,4 +79,4 @@ private:
 
 }
 
-#endif // NODEINPUTDRAGGER_H
+#endif // OAK_NODEINPUTDRAGGER_H