qc fixes

[akhanf]

Some updates for qc rules:

• closes qc_reg_to_template failing  #113 (at least I can't reproduce that error anymore..)
• adds back the surf qc pngs (needed density wildcards)
• puts dseg qc into a single subplotted png, instead of 3 separate ones
• uses dim=-0.5 for plotting instead of -1 (I was getting very dark images occasionally, this makes it more stable)

[jordandekraker]

Looks great, and it worked in my test case!

We may want to add a .html file combining all of these at some point, but that's maybe a future addition