update getParameters when rebuilding model

[arun3688]

Related issues

#47

Purpose

This PR fixes the bug in getParameters() with new values set by users using setParameters() API. after rebuilding the model using buildModel().

Example

using OMJulia
mod = OMJulia.OMCSession()
ModelicaSystem(mod, "Test.mo", "Test.Example")
getParameters(mod)
## use the setParameters() API 
setParameters(mod, "c=9")
buildModel(mod)
simulate(mod)
c = getParameters(mod, "c")
x = getSolutions(mod, "x")[end][end]
println("c  = ", c, "\tx = ", x)

output

c = 9 x = 0.001109553030142552