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.

tests/gtest/audio_level_meter_test.cpp

@@ -10,21 +10,21 @@
 namespace
 {
 
-olive::core::AudioParams MakeStereoParams()
+olive::core::AudioParams make_stereo_params()
 {
-	return olive::core::AudioParams(48000, olive::core::kChannelLayoutStereo,
-									olive::core::SampleFormat::F32P);
+	return olive::core::AudioParams(48000, olive::core::k_channel_layout_stereo,
+									olive::core::SampleFormat::f32_p);
 }
 
 }
 
 TEST(AudioLevelMeter, Silence)
 {
-	olive::core::SampleBuffer samples(MakeStereoParams(), size_t(480));
+	olive::core::SampleBuffer samples(make_stereo_params(), size_t(480));
 	samples.silence();
 
 	const olive::AudioLevelMeter::Stats stats =
-		olive::AudioLevelMeter::AnalyzeSampleBuffer(samples);
+		olive::AudioLevelMeter::analyze_sample_buffer(samples);
 
 	ASSERT_EQ(stats.channels.size(), 2);
 	EXPECT_TRUE(stats.silence);
@@ -36,7 +36,7 @@ TEST(AudioLevelMeter, Silence)
 
 TEST(AudioLevelMeter, ConstantSignal)
 {
-	olive::core::SampleBuffer samples(MakeStereoParams(), size_t(480));
+	olive::core::SampleBuffer samples(make_stereo_params(), size_t(480));
 	for (int channel = 0; channel < samples.channel_count(); channel++) {
 		float *data = samples.data(channel);
 		for (size_t i = 0; i < samples.sample_count(); i++) {
@@ -45,7 +45,7 @@ TEST(AudioLevelMeter, ConstantSignal)
 	}
 
 	const olive::AudioLevelMeter::Stats stats =
-		olive::AudioLevelMeter::AnalyzeSampleBuffer(samples);
+		olive::AudioLevelMeter::analyze_sample_buffer(samples);
 
 	ASSERT_EQ(stats.channels.size(), 2);
 	EXPECT_FALSE(stats.silence);
@@ -58,14 +58,14 @@ TEST(AudioLevelMeter, ConstantSignal)
 
 TEST(AudioLevelMeter, PerChannelPeaksAndRms)
 {
-	olive::core::SampleBuffer samples(MakeStereoParams(), size_t(4));
+	olive::core::SampleBuffer samples(make_stereo_params(), size_t(4));
 	float left[] = { 0.0f, 0.25f, -0.5f, 1.0f };
 	float right[] = { 0.0f, -0.25f, 0.25f, -0.25f };
 	samples.set(0, left, 4);
 	samples.set(1, right, 4);
 
 	const olive::AudioLevelMeter::Stats stats =
-		olive::AudioLevelMeter::AnalyzeSampleBuffer(samples);
+		olive::AudioLevelMeter::analyze_sample_buffer(samples);
 
 	ASSERT_EQ(stats.channels.size(), 2);
 	EXPECT_DOUBLE_EQ(stats.channels.at(0).peak_linear, 1.0);