void EliminateAll()
{
int released = PrisonerUtil.Eliminate(prison, prisoner => true);
MessageBox.Show(String.Format("All {0} prisoners eliminated.", released));
UpdatePrisoners();
}
void Eliminate(string categoryName)
{
string groupLabel = PrisonerUtil.InternalToInGameCatName(categoryName);
int released = PrisonerUtil.Eliminate(prison, prisoner => prisoner.Category == categoryName);
MessageBox.Show(String.Format("{0} {1} prisoners eliminated.", released, groupLabel));
UpdatePrisoners();
}