User:Brooke Vibber/Math fixes

•  OK 86962 - bugzilla:6722 & bugzilla:18912 - function spacing in HTML, spanish \sen, \operatorname spacing in LaTeX
  • 87117 - followup?
  • 87936 - \sin without params failing
  • 87941 - function spacing <--- these four merged w/ tests in r97034
•  OK 86965 - bugzilla:26380 - \widetilde -- tests & merged
•  OK 87092 - bugzilla:19547 - add ' and ` chars in \text{...} -- is this really sufficient? maybe not but it's ok for now
•  OK 87284 - bugzilla:27324 - add \euro & friends, tweak HTML output of some others -- tests & merged!
•  OK 87298 - bugzilla:27754 - greek chars -- tests & merged!
• MathML going away 87934 - mathml tweak
  • 88030 - mathml followup
  • 88260 - mathml minus