Check if a lump is a valid patch when looking for one by name
requested to merge 1392-2-2-15-attempting-to-draw-a-hud-graphic-with-the-same-lump-name-as-a-lua-script-crashes-the into next
When searching for a patch by name, the file data is validated to ensure the lump is a valid patch. If it's not, the next file(s) with the same name are checked.
Closes #1392