[WIP] Update rollup-plugin-typescript to rollup-plugin-typescript2

[kaffarell]

Will fix #560

[coveralls]

Coverage increased (+1.3%) to 78.082% when pulling e9373d2 on update-typescript-plugin into 97e33f2 on master.

[atodorov]

Will fix #560

Can you add this to commit log and also rebase b/c the latest master branch updated a bunch of other dependencies.

Otherwise LGTM so not sure why the subject says "WIP".

[kaffarell]

Ok, have done the changes. I included WIP in the title because there are a lot of other error down the line. I removed the IE fix but I cannot check if it is used because IE11 is still not working ( #445 ). The problems are typescript errors, every usage of options is using the configuration type but it also has other types.

html5sortable/src/html5sortable.ts

Lines 230 to 237 in a19d778

	* Public sortable object
	* @param {Array|NodeList} sortableElements
	* @param {object|string} options|method
	*/
	export default function sortable (sortableElements, options: configuration|object|string|undefined): sortable {
	// get method string to see if a method is called
	const method = String(options)
	options = options || {}

So I could add a <configuration> before every usage of options but I don't think this is the best solution. I haven't found out when the object string or undefined type on options is used, so we could maybe remove them and write:
options: configuration

[kaffarell]

All the errors look like this:

semantic error TS2339: Property 'items' does not exist on type 'string | void | configuration | HTMLElement'.
  Property 'items' does not exist on type 'string'.

[lukasoppermann]

Hey @kaffarell please verify what I am saying, but I think you could cast options to here:

html5sortable/src/html5sortable.ts

Line 267 in a19d778

options = Object.assign({}, defaultConfiguration, store(sortableElement).config, options)

because at this point it will always be a configuration, correct?

Otherwise we would probably need to add a function that deals with the options parameter and returns a configuration, but try the above mentioned first please.

[lukasoppermann]

@kaffarell any news so this can be made mergable?