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/dialog/rendercancel/rendercancel.cpp

@@ -32,7 +32,7 @@ RenderCancelDialog::RenderCancelDialog(QWidget *parent)
 {
 }
 
-void RenderCancelDialog::RunIfWorkersAreBusy()
+void RenderCancelDialog::run_if_workers_are_busy()
 {
 	if (busy_workers_ > 0) {
 		waiting_workers_ = busy_workers_;
@@ -41,41 +41,41 @@ void RenderCancelDialog::RunIfWorkersAreBusy()
 	}
 }
 
-void RenderCancelDialog::SetWorkerCount(int count)
+void RenderCancelDialog::set_worker_count(int count)
 {
 	total_workers_ = count;
 
-	UpdateProgress();
+	update_progress();
 }
 
-void RenderCancelDialog::WorkerStarted()
+void RenderCancelDialog::worker_started()
 {
 	busy_workers_++;
 
-	UpdateProgress();
+	update_progress();
 }
 
-void RenderCancelDialog::WorkerDone()
+void RenderCancelDialog::worker_done()
 {
 	busy_workers_--;
 
-	UpdateProgress();
+	update_progress();
 }
 
 void RenderCancelDialog::showEvent(QShowEvent *event)
 {
 	QDialog::showEvent(event);
 
-	UpdateProgress();
+	update_progress();
 }
 
-void RenderCancelDialog::UpdateProgress()
+void RenderCancelDialog::update_progress()
 {
 	if (!total_workers_ || !isVisible()) {
 		return;
 	}
 
-	SetProgress(
+	set_progress(
 		qRound(100.0 * static_cast<double>(waiting_workers_ - busy_workers_) /
 			   static_cast<double>(waiting_workers_)));