message: Fix nodegraph implementations for extract nodes
diff: <switch name="N_sw_color2" type="float">
  <input name="in1" type="float" nodename="N_r_color2"/>
  <input name="in2" type="float" nodename="N_a_color2"/>
  - <parameter name="which" type="float" interfacename="index"/>
  + <parameter name="which" type="integer" interfacename="index"/>
  </switch>
  <output name="N_out_color2" type="float" nodename="N_sw_color2"/>
  </nodegraph>
  <switch name="N_sw_vector2" type="float">
  <input name="in1" type="float" nodename="N_r_vector2"/>
  <input name="in2" type="float" nodename="N_g_vector2"/>
  - <parameter name="which" type="float" interfacename="index"/>
  + <parameter name="which" type="integer" interfacename="index"/>
  </switch>
  <output name="N_out_vector2" type="float" nodename="N_sw_vector2"/>
  </nodegraph>
  <input name="in1" type="float" nodename="N_r_color3"/>
  <input name="in2" type="float" nodename="N_g_color3"/>
  <input name="in3" type="float" nodename="N_b_color3"/>
  - <parameter name="which" type="float" interfacename="index"/>
  + <parameter name="which" type="integer" interfacename="index"/>
  </switch>
  <output name="N_out_color3" type="float" nodename="N_sw_color3"/>
  </nodegraph>
  <input name="in1" type="float" nodename="N_r_vector3"/>
  <input name="in2" type="float" nodename="N_g_vector3"/>
  <input name="in3" type="float" nodename="N_b_vector3"/>
  - <parameter name="which" type="float" interfacename="index"/>
  + <parameter name="which" type="integer" interfacename="index"/>
  </switch>
  <output name="N_out_vector3" type="float" nodename="N_sw_vector3"/>
  </nodegraph>
  <input name="in2" type="float" nodename="N_g_color4"/>
  <input name="in3" type="float" nodename="N_b_color4"/>
  <input name="in4" type="float" nodename="N_a_color4"/>
  - <parameter name="which" type="float" interfacename="index"/>
  + <parameter name="which" type="integer" interfacename="index"/>
  </switch>
  <output name="N_out_color4" type="float" nodename="N_sw_color4"/>
  </nodegraph>
  <input name="in2" type="float" nodename="N_g_vector4"/>
  <input name="in3" type="float" nodename="N_b_vector4"/>
  <input name="in4" type="float" nodename="N_a_vector4"/>
  - <parameter name="which" type="float" interfacename="index"/>
  + <parameter name="which" type="integer" interfacename="index"/>
  </switch>
  <output name="N_out_vector4" type="float" nodename="N_sw_vector4"/>
  </nodegraph>
  