Changes should display equal-width content columns to make changes more obvious

[neophiliac]

Since the 'current' and 'previous' columns are not the same width, the content wraps differently. This makes it very difficult to discover the differences when they are subtle. Highlighting the changes would solve this problem better than equal column widths

[igal]

I've pushed a change to CSS that tries to make the columns of equal size, which helps a lot.

A clarification on what's going on at <pdxruby.org/changes> is that "agenda" value for change #107 is that the line endings changed when I submitted the form, but not the text. I may want to make the system recognize such changes and either skip displaying them or display them with highlights.

Adding highlighting to the diff would help a lot, but is trickier to do -- I recall doing something of this sort before with a diff-lcs algorithm.