Implicit type conversion for parameters don't work

[mchitre]

Example:

Agent:

@agent struct Physical <: Agent
  propagationSpeed::Float64 = 1500
end

Fjage.params(::Physical) = [
  "org.arl.unet.phy.PhysicalParam.propagationSpeed" => :propagationSpeed
]

results in:

> phy.propagationSpeed
1500
> phy.propagationSpeed = 330   # should work, but fails
WARNING: Parameter propagationSpeed set to 1500
> phy.propagationSpeed = 330.0
330.0

The second one fails because:

julia> setfield!(a, :propagationSpeed, 330)
ERROR: TypeError: in setfield!, expected Float64, got a value of type Int64
Stacktrace:
 [1] top-level scope
   @ REPL[9]:1

julia> setfield!(a, :propagationSpeed, 330.0)
330.0