Fix typings to match the actual exported api format

[soft-decay]

@alexprey As you said, the typings should be updated to match the actual api.

First thing I found is :

export interface SvelteDataItem extends ISvelteItem {
// ...
/**
 * The default value of property, if provided.
 */
value?: any;
// ...
}

but the exported key is actually defaultValue (see the example Button).

Which one should be kept?

[alexprey]

Thanks for that catch, I'm fix it. And also update the API for default value of optional parameter

[soft-decay]

I just saw you pushed modifications for the typings, but I made a mistake when I renamed SvelteMethodArgumentItem to SvelteMethodParamItem.

It should be:

/**
 * @deprecated
 */
export type SvelteMethodArgumentItem = SvelteMethodParamItem;

and you can delete type SvelteArgItem and type SvelteArgumentItem, I added them by mistake in #40, so they were never released.

[alexprey]

Ok, thanks for note about that, I'm remove this types from typings file.