Changes made in response to feedback

I've made / am going to make a few changes to the wiki in response to feedback.

• Users have pointed out that better comment extensions than mw:Extension:Comments exist, namely mw:Extension:CommentStreams. I'll be moving the wiki to that extension by Tuesday.
• I've made a few changes for the sake of accessibility:
  • The link colour has been altered, to improve contrast.
  • The maximum width of text elements has been set to 750px, for ease of reading. Tables are unaffected.
  • The font has been changed from Segoe UI to Helvetica Neue.