Umd support

[reppners]

These changes introduce UMD support with declaration file enhancement by using rollup on the typescript ES2015 module output.

Basically it does the same as PR #98 (kudos to @dpogue for paving the path) but without removing the toolchain used for development/release workflow.

Will test the changes in a webpack-based project tomorrow. Global usage in demo is working fine.

• global
• webpack
• systemjs / jspm

related issues #83, #94

[timruffles]

Looks great, and I'll also second your thanks to @dpogue for his excellent work!

[reppners]

Thx. Just recognized that rollup with typescript plugin won't resolve const enum's which raises output size. Looks like sourcemaps can be maintained by using another plugin and build with tsc upfront which is needed anyways for having declaration files.

rollup/rollup-plugin-typescript#28 (comment)

[dpogue]

Just checked the rollup config on my branch and it looked like I had to pull in rollup-plugin-sourcemaps (Although worth noting that I was running TypeScript with tsc instead of through rollup-plugin-typescript)

Currently we are getting a warning in WebPack about sourcemaps:

WARNING in ./~/drag-drop-polyfill/release/drag-drop-polyfill.min.js
(Emitted value instead of an instance of Error) Cannot find SourceMap drag-drop-polyfill.min.js.map: Error: Can't resolve './drag-drop-polyfill.min.js.map' in '<PROJECT>/node_modules/drag-drop-polyfill/release'
 @ ./demo/app.ts 11:0-54

[reppners]

Build now uses tsc followed by rollup with rollup-plugin-sourcemaps. Release files now include sourcemaps.

[reppners]

Last tests with jspm/systemjs and declaration file support were succesful. export as namespace works as intended.