Use tslib for smaller modules

[roddolf]

The library tslib contains the helpers of TypeScript (for example the extension of classes, or polyfills for ES5 compatibility).

If the library is applied as dependency and adding the flag --importHelpers in the configuration, it will generate smaller modules and bundles, since it will remove repeated code and it'll add less overhead when parsing the javascript files.

Applying the same configuration to SPARQLER will also reduce code, since both will depend in tslib for the helpers