Disentangle boolean flags from input variables

[felipeZ]

Problem

The user input is merged with the defaults of a given calculator to form a hierarchical Property object. The problem arises when the initialization method of the calculator must choose between procedure A or B, and there is a default property associated with A or B, for instance A.foo or B.bar.
During the initialization the following pseudo-code is run:

const Property& input = ....
if (input.exists("foo")){
  run(A)
} else {
  run(B)
}

Because A.foo is always present as default, the program will always run A.

Solution

1. Create a flag that indicates whether A or B must be run, disentangling the properties from the boolean flags.
2. Remove all the calls to exists avoiding collisions with the default values.