* Additional changes for PR #477

* clang-format all files
* Make it clear in avifenc syntax that -p signals prem in the resultant AVIF
* Fix tref prem parsing to match tref auxl parsing (same syntax/box)
* parenthesize binops in assignments (style)
* Continue new convertResult pattern in avifImageYUVToRGB instead of early-out
* Replace pColorIrefType/pColorIrefToID with new avifEncoderDataFindItemByID() call, as
  avifEncoderItem* mem storage may shift during new calls to avifEncoderDataCreateItem() so
  deep pointers into them during this is bad, plus this happens to remove accidental
  Hungarian notation, which is good

src/read.c

diff --git a/src/read.c b/src/read.c
index 941b20d..db18c9a 100644
--- a/src/read.c
+++ b/src/read.c
@@ -2033,12 +2033,13 @@
 
         if (!memcmp(header.type, "auxl", 4)) {
             uint32_t toID;
-            CHECK(avifROStreamReadU32(&s, &toID));                       // unsigned int(32) track_IDs[]
+            CHECK(avifROStreamReadU32(&s, &toID));                       // unsigned int(32) track_IDs[];
             CHECK(avifROStreamSkip(&s, header.size - sizeof(uint32_t))); // just take the first one
             track->auxForID = toID;
         } else if (!memcmp(header.type, "prem", 4)) {
             uint32_t byID;
-            CHECK(avifROStreamReadU32(&s, &byID));                       // unsigned int(32) to_item_ID
+            CHECK(avifROStreamReadU32(&s, &byID));                       // unsigned int(32) track_IDs[];
+            CHECK(avifROStreamSkip(&s, header.size - sizeof(uint32_t))); // just take the first one
             track->premByID = byID;
         } else {
             CHECK(avifROStreamSkip(&s, header.size));
@@ -2613,7 +2614,7 @@
         decoder->image->width = colorTrack->width;
         decoder->image->height = colorTrack->height;
         decoder->alphaPresent = (alphaTrack != NULL);
-        decoder->image->alphaPremultiplied = decoder->alphaPresent && colorTrack->premByID == alphaTrack->id;
+        decoder->image->alphaPremultiplied = decoder->alphaPresent && (colorTrack->premByID == alphaTrack->id);
     } else {
         // Create from items
 
@@ -2770,7 +2771,7 @@
             decoder->image->height = 0;
         }
         decoder->alphaPresent = (alphaItem != NULL);
-        decoder->image->alphaPremultiplied = decoder->alphaPresent && colorItem->premByID == alphaItem->id;
+        decoder->image->alphaPremultiplied = decoder->alphaPresent && (colorItem->premByID == alphaItem->id);
     }
 
     // Sanity check tiles