Extending channel types definitions.

[shamansir]

Despite of #99 and #429

[shamansir]

It happens because their renderers have no edit handler, which is true for all new channels since it is not known which type of editor they require (number input?, checkbox?, etc.). Current (kinda hacky) way to "inherit" an editor from another channel could be:

Rpd.channelrenderer('my/new-channel', 'svg', {
    edit: Rpd.allChannelRenderers['util/number'].edit
});

But probably there should be an easy way to inherit properties from another channel type even in the type definition, so to say "my new channel is extending util/number channel in every possible way, including renderer, but ...".

[shamansir]

It is also possible to just:

Rpd.channelrenderer('my/new-channel', 'svg', Rpd.allChannelRenderers['util/number']['svg']);
Rpd.channelrenderer('my/new-channel', 'html', Rpd.allChannelRenderers['util/number']['html']);

or:

Rpd.allChannelRenderers['my/new-channel'] = Rpd.allChannelRenderers['util/number'];

...Or not to register any new channel, but to override the definition with required methods on node definition step:

Rpd.nodetype('my/new-node', {
    inlets: {
        extendedNumber: { type: `util/number`, adapt: function(v) { return ...; } }
    },
    . . .
});