ui-stats: replace 'enable-stats' setting with 'max-stats'

The new 'max-stats' and 'repo.max-stats' settings makes it possible to
define the maximum statistics period, both globally and per repo. Hence,
it is now feasible to allow statistics on repositories with a high commit
frequency, like linux-2.6, by setting repo.max-stats to e.g. 'month'.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
diff --git a/shared.c b/shared.c
index 37333f0..7382609 100644
--- a/shared.c
+++ b/shared.c
@@ -58,7 +58,7 @@
 	ret->snapshots = ctx.cfg.snapshots;
 	ret->enable_log_filecount = ctx.cfg.enable_log_filecount;
 	ret->enable_log_linecount = ctx.cfg.enable_log_linecount;
-	ret->enable_stats = ctx.cfg.enable_stats;
+	ret->max_stats = ctx.cfg.max_stats;
 	ret->module_link = ctx.cfg.module_link;
 	ret->readme = NULL;
 	return ret;