Changed plot style to improve clarity

This commit makes the dots smaller and changes their style from dots to
crosses. Also, the last dot is now blue instead of black, and the line
is a gradient from 50% black to 100% black so the line progress can be
seen clearer (because the lines cross several times).

Change-Id: Ibc41a4a5c0d27eed01244a450c38945537b93e69
diff --git a/cron/generateCustomData.php b/cron/generateCustomData.php
index 5be2bc0..2055071 100644
--- a/cron/generateCustomData.php
+++ b/cron/generateCustomData.php
@@ -48,8 +48,11 @@
     $file = tmpfile();
     $fileName = stream_get_meta_data($file)['uri'];
-    foreach ($summary as $row)
-      fwrite($file, $row["data"]." ".$row["ia14"]." ".$row["rho7"]."\n");
+    $i = 0;
+    foreach ($summary as $row) {
+      fwrite($file, $row["data"]." ".$row["ia14"]." ".$row["rho7"]." ".$i."\n");
+      ++$i;
+    }
     // Cridem al gnuplot perquè generi la gràfica
     shell_exec("gnuplot -c generateCustomGraph.gnu \"".escapeshellcmd($area["name"])."\" \"".escapeshellcmd($area["codename"])."\" \"".escapeshellcmd($fileName)."\"");