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/nodeview/nodeviewedge.h

@@ -19,8 +19,8 @@
 
 ***/
 
-#ifndef NODEEDGEITEM_H
-#define NODEEDGEITEM_H
+#ifndef OAK_NODEEDGEITEM_H
+#define OAK_NODEEDGEITEM_H
 
 #include <QGraphicsPathItem>
 #include <QPalette>
@@ -76,7 +76,7 @@ public:
 
 	void set_to_item(NodeViewItem *i);
 
-	void Adjust();
+	void adjust();
 
 	/**
    * @brief Set the connected state of this line
@@ -88,9 +88,9 @@ public:
    * Using SetEdge() automatically sets this to true. Under most circumstances this should be left alone, and only
    * be set when an edge is being created/dragged.
    */
-	void SetConnected(bool c);
+	void set_connected(bool c);
 
-	bool IsConnected() const
+	bool is_connected() const
 	{
 		return connected_;
 	}
@@ -100,17 +100,17 @@ public:
    *
    * Changes color of edge.
    */
-	void SetHighlighted(bool e);
+	void set_highlighted(bool e);
 
 	/**
    * @brief Set points to create curve from
    */
-	void SetPoints(const QPointF &start, const QPointF &end);
+	void set_points(const QPointF &start, const QPointF &end);
 
 	/**
    * @brief Set whether edges should be drawn as curved or as straight lines
    */
-	void SetCurved(bool e);
+	void set_curved(bool e);
 
 protected:
 	virtual void paint(QPainter *painter,
@@ -118,9 +118,9 @@ protected:
 					   QWidget *widget = nullptr) override;
 
 private:
-	void Init();
+	void init();
 
-	void UpdateCurve();
+	void update_curve();
 
 	Node *output_;
 
@@ -146,4 +146,4 @@ private:
 
 }
 
-#endif // NODEEDGEITEM_H
+#endif // OAK_NODEEDGEITEM_H