Remove some redundancy from the DValue hierarchy: all subclasses had a 'type' field and identical implementations of virtual function getType(). Move these to DValue itself, and make getType() non-virtual.

module tangotests.ina1;

import tango.stdc.stdio;

void main()
{
    int alder;
    printf("Hvor gammel er du?\n");
    scanf("%d", &alder);
    printf("om 10 år er du %d\n", alder + 10);
}