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/multicam/multicamwidget.h

@@ -19,8 +19,8 @@
 
 ***/
 
-#ifndef MULTICAMWIDGET_H
-#define MULTICAMWIDGET_H
+#ifndef OAK_MULTICAMWIDGET_H
+#define OAK_MULTICAMWIDGET_H
 
 #include "multicamdisplay.h"
 #include "node/input/multicam/multicamnode.h"
@@ -34,24 +34,24 @@ class MulticamWidget : public TimeBasedWidget {
 public:
 	explicit MulticamWidget(QWidget *parent = nullptr);
 
-	MulticamDisplay *GetDisplayWidget() const
+	MulticamDisplay *get_display_widget() const
 	{
 		return display_;
 	}
 
-	void SetMulticamNode(ViewerOutput *viewer, MultiCamNode *n, ClipBlock *clip,
-						 const rational &time);
+	void set_multicam_node(ViewerOutput *viewer, MultiCamNode *n, ClipBlock *clip,
+						 const Rational &time);
 
 protected:
 	virtual void ConnectNodeEvent(ViewerOutput *n) override;
 	virtual void DisconnectNodeEvent(ViewerOutput *n) override;
-	virtual void TimeChangedEvent(const rational &t) override;
+	virtual void TimeChangedEvent(const Rational &t) override;
 
 signals:
-	void Switched();
+	void switched();
 
 private:
-	void SetMulticamNodeInternal(ViewerOutput *viewer, MultiCamNode *n,
+	void set_multicam_node_internal(ViewerOutput *viewer, MultiCamNode *n,
 								 ClipBlock *clip);
 
 	void Switch(int source, bool split_clip);
@@ -65,7 +65,7 @@ private:
 	ClipBlock *clip_;
 
 	struct MulticamNodeQueue {
-		rational time;
+		Rational time;
 		ViewerOutput *viewer;
 		MultiCamNode *node;
 		ClipBlock *clip;
@@ -74,9 +74,9 @@ private:
 	std::list<MulticamNodeQueue> play_queue_;
 
 private slots:
-	void DisplayClicked(const QPoint &p);
+	void display_clicked(const QPoint &p);
 };
 
 }
 
-#endif // MULTICAMWIDGET_H
+#endif // OAK_MULTICAMWIDGET_H