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/oiio/oiiodecoder.h

@@ -19,8 +19,8 @@
 
 ***/
 
-#ifndef OIIODECODER_H
-#define OIIODECODER_H
+#ifndef OAK_OIIODECODER_H
+#define OAK_OIIODECODER_H
 
 #include <OpenImageIO/imageio.h>
 #include <OpenImageIO/imagebuf.h>
@@ -39,32 +39,32 @@ public:
 
 	virtual QString id() const override;
 
-	virtual bool SupportsVideo() override
+	virtual bool supports_video() override
 	{
 		return true;
 	}
 
-	virtual FootageDescription Probe(const QString &filename,
+	virtual FootageDescription probe(const QString &filename,
 									 CancelAtom *cancelled) const override;
 
 protected:
-	virtual bool OpenInternal() override;
+	virtual bool open_internal() override;
 	virtual TexturePtr
-	RetrieveVideoInternal(const RetrieveVideoParams &p) override;
+	retrieve_video_internal(const RetrieveVideoParams &p) override;
 	virtual FramePtr
-	RetrieveVideoFrameInternal(const RetrieveVideoParams &p) override;
-	virtual void CloseInternal() override;
+	retrieve_video_frame_internal(const RetrieveVideoParams &p) override;
+	virtual void close_internal() override;
 
 private:
 	std::unique_ptr<OIIO::ImageInput> image_;
 
-	static bool FileTypeIsSupported(const QString &fn);
+	static bool file_type_is_supported(const QString &fn);
 
-	bool OpenImageHandler(const QString &fn, int subimage);
+	bool open_image_handler(const QString &fn, int subimage);
 
-	void CloseImageHandle();
+	void close_image_handle();
 
-	static VideoParams GetVideoParamsFromImageSpec(const OIIO::ImageSpec &spec);
+	static VideoParams get_video_params_from_image_spec(const OIIO::ImageSpec &spec);
 
 	PixelFormat pix_fmt_;
 	OIIO::TypeDesc::BASETYPE oiio_pix_fmt_;
@@ -72,9 +72,9 @@ private:
 	Frame buffer_;
 	RetrieveVideoParams last_params_;
 
-	static QStringList supported_formats_;
+	static QStringList supported_formats;
 };
 
 }
 
-#endif // OIIODECODER_H
+#endif // OAK_OIIODECODER_H