amended outer constructor for Settings()

CONTRIBUTING.md

@@ -85,3 +85,28 @@ TODO
 * If a PR is not finished yet and should not be reviewed yet then it should be opened as DRAFT 
   (in this way maintainers will know that they can ignore such PR until it is made non-draft or the author
   asks for a review).
+
+## Contribution Ideas
+
+Models for:
+* Breakaway (currently simple like acceleration)
+* braking (currently constant braking with a certain value)
+* inhomogeneous mass band (consider non-uniform mass distribution (cf. Wende, 2003 p. 96f.))
+
+More exact calculation of resistances for:
+* the track (e.g. including curves, switches, tunnels) 
+* for the train (e.g. there are vehicle resistance equations especially for high-speed trains, which are not yet considered in the tool (cf. Wende, 2003 p. 152 f.))
+
+Input/calculation of tractive force (currently only tractive force-speed pairs. This could be extended to include tractive force functions that apply to specific velocity ranges (cf. Brünger, et al., 2014 p. 69).
+
+Calculation of energy, cf. (Wende, 2003 p. 324).
+
+switching between different step variables in one train run or implementation of variable step size (currently it is necessary to choose between s, t and v and to specify a step size that becomes smaller at intersections, but is otherwise constant)
+
+Driver behaviour, in order to be able to determine the driving behavior of the vehicles more realistically.
+
+Energy-saving driving.
+
+good plots would be nice
+
+Pluto notebook show case

src/constructors.jl

@@ -18,16 +18,15 @@ julia> my_settings = Settings() # will generate default settings
 Settings(:mass_point, :distance, 20, 3, :running_time, :dataframe)
 ```
 """
-function Settings(file="DEFAULT")
-
-    ## default values
-    massModel    = :mass_point
-    stepVariable = :distance
-    stepSize     = 20
-    approxLevel  = 3
-    outputDetail = :running_time
-    outputFormat = :dataframe
-
+function Settings(
+            file         = "DEFAULT";
+            massModel::Symbol    = :mass_point,
+            stepVariable::Symbol = :distance,
+            stepSize::Number     = 20,
+            approxLevel::Number  = 3,
+            outputDetail::Symbol = :running_time,
+            outputFormat::Symbol = :dataframe
+        )
     ## load from file
     if file != "DEFAULT"