Hidden parameters for blocks

[b4zz4]

example:

<BlockGenus name="df_led_pwm" kind="command" color="0 168 0" initlabel="bg.df_led_pwm">
[...]
<DefaultArg genus-name="number" label="128" hidden="true" />
[...]
</BlockGenus>

This allows to use an alone program for several BlockGenus