message: allow partial params in .createParams helper
diff: @@ -61,9 +61,9 @@ namespace StructureRepresentation3DHelpers {
  export function createParams<R extends RepresentationProvider<Structure, any, any>, C extends ColorTheme.Provider<any>, S extends SizeTheme.Provider<any>>(
  ctx: PluginContext, structure: Structure, params: {
  - repr?: R | [R, (r: R, ctx: ThemeRegistryContext, s: Structure) => RepresentationProvider.ParamValues<R>],
  - color?: C | [C, (c: C, ctx: ThemeRegistryContext) => ColorTheme.ParamValues<C>],
  - size?: S | [S, (c: S, ctx: ThemeRegistryContext) => SizeTheme.ParamValues<S>]
  + repr?: R | [R, (r: R, ctx: ThemeRegistryContext, s: Structure) => Partial<RepresentationProvider.ParamValues<R>>],
  + color?: C | [C, (c: C, ctx: ThemeRegistryContext) => Partial<ColorTheme.ParamValues<C>>],
  + size?: S | [S, (c: S, ctx: ThemeRegistryContext) => Partial<SizeTheme.ParamValues<S>>]
  }): StateTransformer.Params<StructureRepresentation3D> {
  const themeCtx = ctx.structureRepresentation.themeCtx
  @@ -79,16 +79,18 @@ namespace StructureRepresentation3DHelpers {
  const color = params.color
  ? params.color instanceof Array ? params.color[0] : params.color
  : themeCtx.colorThemeRegistry.get(repr.defaultColorTheme);
  + const colorDefaultParams = PD.getDefaultValues(color.getParams(themeCtx))
  const colorParams = params.color instanceof Array
  - ? params.color[1](color as C, themeCtx)
  - : PD.getDefaultValues(color.getParams(themeCtx));
  + ? { ...colorDefaultParams, ...params.color[1](color as C, themeCtx) }
  + : colorDefaultParams;
  const size = params.size
  ? params.size instanceof Array ? params.size[0] : params.size
  : themeCtx.sizeThemeRegistry.get(repr.defaultSizeTheme);
  + const sizeDefaultParams = PD.getDefaultValues(size.getParams(themeCtx))
  const sizeParams = params.size instanceof Array
  - ? params.size[1](size as S, themeCtx)
  - : PD.getDefaultValues(size.getParams(themeCtx));
  + ? { ...sizeDefaultParams, ...params.size[1](size as S, themeCtx) }
  + : sizeDefaultParams;
  return ({
  type: { name: ctx.structureRepresentation.registry.getName(repr), params: reprParams },
  