replace cat with hg cat to get bytes_per_card for different revisions

Makefile

@@ -616,8 +616,8 @@ ai/benchmark.rnd:
 exp/zermelo.tsv: $(wildcard exp/136*.log)
 	awk -f exp/extract_games.awk $^ | ./exp/whr.rb | tac > $@
 
-bytes_per_card:
-	echo `cat release/Magarena/scripts/* | sed 's/^[[:space:]]*//' | wc -c` \
+bytes_per_card.%:
+	echo `hg cat -r $* release/Magarena/scripts/ | sed 's/^[[:space:]]*//' | wc -c` \
 	/ \
 	`ls -1 release/Magarena/scripts/*.txt | wc -l` \
 	| bc -l