Updated default setings.

* Simple trees, gems, soil, stone, and pets are all on.
* Invaders have base skill changed to zero.
* Default theme changed to 'BLUE'.

See http://www.bay12forums.com/smf/index.php?topic=133174.msg4854894#msg4854894 for discussion.
Merge branch 'master' into nerfed_diseases

* master:
  Updated default setings.