- make attribute accessing easier, you can now use attr(<key>) or   [<key>] and <key> can be a symbol (_ gets converted to :) or string.
- make attribute accessing easier, you can now use attr(<key>) or
  [<key>] and <key> can be a symbol (_ gets converted to :) or string.

 These calls are all equivalent:  
   solvable.attr("foo:bar")
   solvable.attr(:foo_bar)
   solvable["foo:bar"]
   solvable[:foo_bar]
   
- fix accessing an array attribute



ryppl/sat-solver,ryppl/sat-solver,ryppl/sat-solver,ryppl/sat-solver,ryppl/sat-solver