remove non images early (#1007)

kindlecomicconverter/shared.py

@@ -48,12 +48,6 @@ class HTMLStripper(HTMLParser):
 def getImageFileName(imgfile):
     name, ext = os.path.splitext(imgfile)
     ext = ext.lower()
-    if (name.startswith('.') and len(name) == 1):
-        return None
-    if name.startswith('._'):
-        return None
-    if ext not in ['.png', '.jpg', '.jpeg', '.gif', '.webp', '.jp2', '.j2k', '.jpx']:
-        return None
     return [name, ext]