Agent Birth from Host Functions

Agents can be created using host step functions.

FLAMEGPU_STEP_FUNCTION(BasicOutput) {
    // Get the agent type 'agent'
    auto t = FLAMEGPU->agent("agent");

    // Create NEW_AGENT_COUNT new 'agent' agents with 'x' set to 1.0f
    for (unsigned int i = 0; i < NEW_AGENT_COUNT; ++i)
        t.newAgent().setVariable<float>("x", 1.0f);
}