cleanup termination parameters
cleanup termination parameters

- make the default values the same type as user-specified ones
- enforce MaxTime > MaxFuncEvals > MaxSteps priority
  by deleting the parameters with lower priority if higher-priority
  one is specified

JuliaPackageMirrors/BlackBoxOptim.jl,tkelman/BlackBoxOptim.jl,tkelman/BlackBoxOptim.jl,JuliaPackageMirrors/BlackBoxOptim.jl,multidis/BlackBoxOptim.jl,multidis/BlackBoxOptim.jl,tkelman/BlackBoxOptim.jl,multidis/BlackBoxOptim.jl,JuliaPackageMirrors/BlackBoxOptim.jl