mason/.perl-lib/TrivGal.pm (%SIZE): Modify and extend the available sizes.

mason/.perl-lib/TrivGal.pm (%SIZE): Modify and extend the available sizes.

I want to support fetching main view images scaled adaptively for the
window size.  This involves having many more image sizes.  I considered
abolishing the `%SIZE' list, but realized that this wouldn't work
because `Image::scale' needs to pass back a size name in its lazy-
thumbnailing query string.

Instead, just add lots of new sizes.  The scale factor is about 3/2 in
each case.  Making the factor more-or-less uniform involved changing a
couple of existing sizes: `bigthumb' shrunk a little from 228 to 216;
`view' used to be 1200, but is replaced by `medium', which is
significantly smaller at 1080.  I know that `small' and `embed' are
already used externally, and have preserved these names and their
values (though the values already fit well into the sequence, so this
wasn't a hardship).

I'd have preferred to have more mall words and fewer big words in the
list, but I was constrained by the existing value of `small'.  It seems
that there are just more words for being very big than being very small
anyway.