Rastering/anti-aliasing error in TOM plot

[avcarr2]

This issue is created to address the bug where the TOM plot is generated with a white line running across it. I've looked into this pretty deeply, but I can't figure out where the error is coming from. There are three possibilities:

1. The error is caused by the R graphics device.
2. The error is caused by an interaction between the internet browser that MetaNetwork is running in and R.
3. The error is completely caused by the internet browser in which MetaNetwork is running.

I haven't personally encountered this issue yet, but it has been reported a few times. I am using Google Chrome as the browser in which MetaNetwork is running. I will continue looking into this bug. It appears that the TOM plot is the only one running into this issue. It is also the only plot output as a png file rather than a pdf. I'm going to change the TOM plot output file extension to jpg and see if that solves the issue by bypassing any issues with png file writing.