The eval command allows the evaluation of simulation results by creating
multi-dimensional tables with names and values which are usable as input for
graph-creating tools like gnuplot and xmgrace.

Input for this command is

* the definition of columns which should appear in the generated tables. For
  this the option [@o]--column-definition is used. Each column has a number, a type
  and - depending on the type - additional parameters which defines what appears
  in this column. 
 
** The column number starts with 0 and the column numbers are consecutive
   without holes.

** The type may be either a simulation-parameter, a result-path or a batch
   number. The type
   simulation-parameter may be abbreviated with sp, the type result-path may be
   abbreviated with rp and the type batch-number may be abbreviated with bn.

** The third argument depends an the type: When using a simulation parameter,
   the additional parameter is the name of the simulation parameter. When using
   a result-path, the path is the additional parameter. The type batch-number
   has no additional argument.

* One or more result-path definitions (Option [@o]--result-path) which may be
  referenced in the column definitions.

* Further options

SimTree generates a list of lines starting with a headline followed by data
lines which contain the result ordered in the columns defined.

A evaluation is only valid when all given data sources in the column definitions
result in the same number of values.
