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/ui/colorcoding.h

@@ -19,8 +19,8 @@
 
 ***/
 
-#ifndef COLORCODING_H
-#define COLORCODING_H
+#ifndef OAK_COLORCODING_H
+#define OAK_COLORCODING_H
 
 #include <olive/core/core.h>
 #include <QObject>
@@ -34,39 +34,39 @@ class ColorCoding : public QObject {
 	Q_OBJECT
 public:
 	enum Code {
-		kRed,
-		kMaroon,
-		kOrange,
-		kBrown,
-		kYellow,
-		kOlive,
-		kLime,
-		kGreen,
-		kCyan,
-		kTeal,
-		kBlue,
-		kNavy,
-		kPink,
-		kPurple,
-		kSilver,
-		kGray
+		k_red,
+		k_maroon,
+		k_orange,
+		k_brown,
+		k_yellow,
+		k_olive,
+		k_lime,
+		k_green,
+		k_cyan,
+		k_teal,
+		k_blue,
+		k_navy,
+		k_pink,
+		k_purple,
+		k_silver,
+		k_gray
 	};
 
-	static QString GetColorName(int c);
+	static QString get_color_name(int c);
 
-	static Color GetColor(int c);
+	static Color get_color(int c);
 
-	static Qt::GlobalColor GetUISelectorColor(const Color &c);
+	static Qt::GlobalColor get_ui_selector_color(const Color &c);
 
 	static const QVector<Color> &standard_colors()
 	{
-		return colors_;
+		return colors;
 	}
 
 private:
-	static QVector<Color> colors_;
+	static QVector<Color> colors;
 };
 
 }
 
-#endif // COLORCODING_H
+#endif // OAK_COLORCODING_H