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/slider/base/numericsliderbase.h

@@ -19,8 +19,8 @@
 
 ***/
 
-#ifndef NUMERICSLIDERBASE_H
-#define NUMERICSLIDERBASE_H
+#ifndef OAK_NUMERICSLIDERBASE_H
+#define OAK_NUMERICSLIDERBASE_H
 
 #include "sliderbase.h"
 
@@ -32,41 +32,41 @@ class NumericSliderBase : public SliderBase {
 public:
 	NumericSliderBase(QWidget *parent = nullptr);
 
-	void SetLadderElementCount(int b)
+	void set_ladder_element_count(int b)
 	{
 		ladder_element_count_ = b;
 	}
 
-	void SetDragMultiplier(const double &d);
+	void set_drag_multiplier(const double &d);
 
-	void SetOffset(const QVariant &v);
+	void set_offset(const QVariant &v);
 
-	bool IsDragging() const;
+	bool is_dragging() const;
 
 protected:
-	const QVariant &GetOffset() const
+	const QVariant &get_offset() const
 	{
 		return offset_;
 	}
 
-	virtual QVariant AdjustDragDistanceInternal(const QVariant &start,
+	virtual QVariant adjust_drag_distance_internal(const QVariant &start,
 												const double &drag) const;
 
-	void SetMinimumInternal(const QVariant &v);
+	void set_minimum_internal(const QVariant &v);
 
-	void SetMaximumInternal(const QVariant &v);
+	void set_maximum_internal(const QVariant &v);
 
-	virtual bool ValueGreaterThan(const QVariant &lhs,
+	virtual bool value_greater_than(const QVariant &lhs,
 								  const QVariant &rhs) const;
 
-	virtual bool ValueLessThan(const QVariant &lhs, const QVariant &rhs) const;
+	virtual bool value_less_than(const QVariant &lhs, const QVariant &rhs) const;
 
-	virtual bool CanSetValue() const override;
+	virtual bool can_set_value() const override;
 
 private:
-	bool UsingLadders() const;
+	bool using_ladders() const;
 
-	virtual QVariant AdjustValue(const QVariant &value) const override;
+	virtual QVariant adjust_value(const QVariant &value) const override;
 
 	SliderLadder *drag_ladder_;
 
@@ -93,18 +93,18 @@ private:
 	/**
    * @brief An effects slider somewhere is being dragged
    */
-	static bool effects_slider_is_being_dragged_;
+	static bool effects_slider_is_being_dragged;
 
 private slots:
-	void LabelPressed();
+	void label_pressed();
 
-	void RepositionLadder();
+	void reposition_ladder();
 
-	void LadderDragged(int value, double multiplier);
+	void ladder_dragged(int value, double multiplier);
 
-	void LadderReleased();
+	void ladder_released();
 };
 
 }
 
-#endif // NUMERICSLIDERBASE_H
+#endif // OAK_NUMERICSLIDERBASE_H