Fix positionY not reading the full value when gridY is larger than de…

…fault

Fixes PlugY positionY values being read incorrectly, as well as any modded D2 saves that change Inventory.txt to increase gridY. In vanilla D2, the Y value never uses the 4th bit since the largest used gridY in Inventory.txt is 8, which lead to the 4th bit erroneously being labeled 'unknown' in previous d2s format guides. Whoops!

Closes #9. Thanks to @oaken-source for finding the problem.

docs/formats/d2.md

@@ -75,8 +75,7 @@ Bit Offset | Size (bits) | Description
 58 | 3 | Item location. See [the `locationID` field of the `d2item` struct](/api.html#structd2item).
 61 | 4 | Item equipped location. See [the `equippedID` field of the `d2item` struct](/api.html#structd2item).
 65 | 4 | Item position X coordinate
-69 | 3 | Item position Y coordinate
-72 | 1 | Unknown
+69 | 4 | Item position Y coordinate
 73 | 3 | Panel containing the item. See [the `panelID` field of the `d2item` struct](/api.html#structd2item).
 76 | ... | If the item is an ear (bit offset 32), then see "Ear", otherwise skip to "Non-Ear"
 

src/d2itemreader.c

@@ -551,9 +551,7 @@ CHECK_RESULT d2err d2item_parse_single(const uint8_t* const data, size_t dataSiz
 	// offset 65
 	item->positionX = (uint8_t)d2bitreader_read(&br, 4);
 	// offset 69
-	item->positionY = (uint8_t)d2bitreader_read(&br, 3);
-	// offset 72
-	d2bitreader_read(&br, 1);
+	item->positionY = (uint8_t)d2bitreader_read(&br, 4);
 	// offset 73, if item is neither equipped or in the belt, this tells us where it is.
 	item->panelID = (uint8_t)d2bitreader_read(&br, 3);