Patch 5187 by Goba:
 - puts the long multiline help text into one string
 - fixes the ambiquity of calling two things on the same name: "custom block"
   now the user customizeable blocks are called custom blocks, and the admin
   defined blocks are called Administator Defined Blocks
 - added info on throttle to the explanation on when a block is displyed
 - also fixing some small typos