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/plugin_support_clip_test.cpp

@@ -2,11 +2,11 @@
 
 #include "ofxImageEffect.h"
 #include "ofxhClip.h"
-#include "pluginSupport/OliveClip.h"
+#include "pluginSupport/oliveclip.h"
 
 namespace
 {
-olive::VideoParams MakeParams(int width, int height,
+olive::VideoParams make_params(int width, int height,
 							  olive::core::PixelFormat format, int channels,
 							  bool premultiplied)
 {
@@ -24,12 +24,12 @@ TEST(PluginSupportClip, PropertyGetters)
 {
 	OFX::Host::ImageEffect::ClipDescriptor desc(kOfxImageEffectOutputClipName);
 	olive::VideoParams params =
-		MakeParams(1920, 1080, olive::core::PixelFormat::U16, 3, false);
-	params.set_pixel_aspect_ratio(olive::core::rational(2, 1));
-	params.set_frame_rate(olive::core::rational(30, 1));
+		make_params(1920, 1080, olive::core::PixelFormat::u16, 3, false);
+	params.set_pixel_aspect_ratio(olive::core::Rational(2, 1));
+	params.set_frame_rate(olive::core::Rational(30, 1));
 	params.set_start_time(2);
 	params.set_duration(4);
-	params.set_interlacing(olive::VideoParams::kInterlacedTopFirst);
+	params.set_interlacing(olive::VideoParams::k_interlaced_top_first);
 
 	olive::plugin::OliveClipInstance clip(nullptr, desc, params);
 
@@ -60,7 +60,7 @@ TEST(PluginSupportClip, GetImageClampsBoundsAndCachesOutput)
 {
 	OFX::Host::ImageEffect::ClipDescriptor desc(kOfxImageEffectOutputClipName);
 	olive::VideoParams params =
-		MakeParams(100, 80, olive::core::PixelFormat::U8, 4, true);
+		make_params(100, 80, olive::core::PixelFormat::u8, 4, true);
 	olive::plugin::OliveClipInstance clip(nullptr, desc, params);
 
 	OfxRectD optional_bounds = { -10.0, -10.0, 200.0, 200.0 };
@@ -79,7 +79,7 @@ TEST(PluginSupportClip, GetImageCachesImageForNonOutput)
 {
 	OFX::Host::ImageEffect::ClipDescriptor desc("Source");
 	olive::VideoParams params =
-		MakeParams(64, 64, olive::core::PixelFormat::U8, 4, false);
+		make_params(64, 64, olive::core::PixelFormat::u8, 4, false);
 	olive::plugin::OliveClipInstance clip(nullptr, desc, params);
 
 	EXPECT_FALSE(clip.getConnected());