Multiple bug fixes in the stats script.

Fix #1, commit f7b205c:
Clean global variable for every iteration, so graphs would contain only relevant information.

Fix #2, commit 34f135a:
Widened legend window, so data sets with longer names are not trimmed.

Fix #3, commit 163ae24:
Removed 'align:center' which made graphs lines to be rendered not on the graph background.