Clean up titles and descriptions

[valentinaschueller]

• upper/lower case:
  • remove title() and capitalize() in as many places as possible
  • only apply such things in the processing tasks, not in presentation task/template
  • if we keep it somewhere, use capitalize() instead of title()
• use "annual mean" instead of "yearly mean" and write it in lower case
• use "over one year" instead of "over one leg" (cf. #36)