Admin/website/TODO

tuned;

- a gentle intro enumeration on Home - "Why Isabelle?"
    * stably running, mature system
    * (something to say about Isar?)
    * big library
    * big community
    * it's free
    * ...
  (to discuss)
- clarify relationship of "overview" and "logics":
    * overview: Isabelle/HOL   
    * logics:   Isabelle system
  (to discuss)

- world_map: automated generation from coordinate data
- world_map: more content in HTML, less in java script