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/codec/conformmanager.h

@@ -16,8 +16,8 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef CONFORMMANAGER_H
-#define CONFORMMANAGER_H
+#ifndef OAK_CONFORMMANAGER_H
+#define OAK_CONFORMMANAGER_H
 
 #include <QMutex>
 #include <QObject>
@@ -31,14 +31,14 @@ namespace olive
 class ConformManager : public QObject {
 	Q_OBJECT
 public:
-	static void CreateInstance()
+	static void create_instance()
 	{
 		if (!instance_) {
 			instance_ = new ConformManager();
 		}
 	}
 
-	static void DestroyInstance()
+	static void destroy_instance()
 	{
 		delete instance_;
 		instance_ = nullptr;
@@ -49,7 +49,7 @@ public:
 		return instance_;
 	}
 
-	enum ConformState { kConformExists, kConformGenerating };
+	enum ConformState { k_conform_exists, k_conform_generating };
 
 	struct Conform {
 		ConformState state;
@@ -62,13 +62,13 @@ public:
      *
      * Thread-safe.
      */
-	Conform GetConformState(const QString &decoder_id,
+	Conform get_conform_state(const QString &decoder_id,
 							const QString &cache_path,
 							const Decoder::CodecStream &stream,
 							const AudioParams &params, bool wait);
 
 signals:
-	void ConformReady();
+	void conform_ready();
 
 private:
 	ConformManager() = default;
@@ -93,16 +93,16 @@ private:
      * @brief Get the destination filename of an audio stream conformed to a set of parameters
      */
 	static QVector<QString>
-	GetConformedFilename(const QString &cache_path,
+	get_conformed_filename(const QString &cache_path,
 						 const Decoder::CodecStream &stream,
 						 const AudioParams &params);
 
-	static bool AllConformsExist(const QVector<QString> &filenames);
+	static bool all_conforms_exist(const QVector<QString> &filenames);
 
 private slots:
-	void ConformTaskFinished(Task *task, bool succeeded);
+	void conform_task_finished(Task *task, bool succeeded);
 };
 
 } // namespace olive
 
-#endif // CONFORMMANAGER_H
+#endif // OAK_CONFORMMANAGER_H