Small ui updates

app/src/main/java/org/koitharu/kotatsu/utils/ext/StringExt.kt

@@ -12,13 +12,13 @@ fun String.longHashCode(): Long {
 	var h = 1125899906842597L
 	val len: Int = this.length
 	for (i in 0 until len) {
-		h = 31 * h + this[i].toLong()
+		h = 31 * h + this[i].code
 	}
 	return h
 }
 
 fun String.removeSurrounding(vararg chars: Char): String {
-	if (length == 0) {
+	if (isEmpty()) {
 		return this
 	}
 	for (c in chars) {
@@ -224,4 +224,4 @@ inline fun <T> StringBuilder.appendAll(
 		}
 		append(transform(item))
 	}
-}
+}