[Beta3] Advertisements widget should set widths correctly (or allow them to be set if required)

Hello,

Under V4 we used "custom locations" for adverts to place them in the sidebar of the homepage. We did not have to do anything fancy and this looked fine with the adverts taking up the full width of the sidebar. Actually, on looking at the adverts more closely, it appears that adverts that are "a bit narrow" are padded on both sides so that they are centralised - and this looks fine. (See https://www.bn.org.uk).

Under V5 using the Advertisement widget the adverts are not padded so are just set to the left of the sidebar. This looks a real mess for slightly narrow adverts. (See https://www.bntest.org.uk)

Sorry, I cannot upload images to show what I mean because the upload fails with "image may violate community standards". Of course, the images are innocent naturist images but no doubt your image scanner has erroneously categorised them as porn. Doh!

Thanks.

John