Add default values for variables in the AMPL file

[GeirHo]

Extend the AMPL file generator to include the default value at the minimum border of the variable domain. Thus if a variable is defined as

var NoInstances >=2 <=15

The default value of two should be given at the end of the statement, so the correct statement should be:

var NoInstances >=2 <= 15 := 2

as this also confirms to the initial configuration deployed by the Optimizer.

[rudi]

Small question about the syntax. The above examples say var NoInstances >=2 <=15 but the code currently generates var NoInstances >=2, <=15. Can you confirm that the code that should be generated is var NoInstances >=2, <=15 := 2 ?