Add trace file name as FMI parameter

[ClemensLinnhoff]

Is your feature request related to a problem? Please describe.
Currently only the trace path can be given and the first trace file in that path is taken as input. That means that only a single trace file in a path can be played.

Describe the solution you'd like
Add an additional parameter for the trace file name. If no name is given, the first in the directory is still played to keep backwards compatibility.