Add filter-by-category functionality (#171)

- Added API for configuring categories
- Added display for categories above page
- Reduced height of page by 1 row to make room for categories
- Added L/R scroll through when there are more categories than columns
- Added pre-filter methods for categories and uncategorised items
- Added categories for (most) items in the default game


Co-authored-by: Oversword <bionc:oversword.co.uk>

.luacheckrc

@@ -14,6 +14,7 @@ read_globals = {
 	"ItemStack", "datastorage",
 
 	"hb",
+	"doors",
 }
 
 files["callbacks.lua"].ignore = { "player", "draw_lite_mode" }