Assignment operators for Character and Creature

Gives the Character and Creature class an assignment operator.
Player assignment calls assignment of Character, which calls assignment of Creature, which copies the effects (blindness).

Creating a new player character assigns a new player object with now effects (see main_menu.cpp), this would override things like player::illness, but not Creature::effects, because the Creature had no assignment operator (and none was called).
Moved the assignment of some values that are no defined in Creature instead of player there.

fixes #5412