Add css alias

Added class alias for bespoke.js so added string-replace-loader before postcss-loader.

__body -> .bespoke-parent
__bg -> .bespoke-backdrop
__section-title -> .bespoke-backdrop.section-title

Sample: https://github.com/hiroppy/fusuma/blob/master/samples/fx/style.css

Also, it will not convert anything other than specific keys, so it has backward compatibility.

Add Slide Transition Animation and Hide Sidebar

Slide Transition Animation

Added support for slide animation.

Demo: https://hiroppy.github.io/fusuma-fx-sample/
Docs: https://github.com/hiroppy/fusuma/blob/master/docs/slide.md#animation

Hide Sidebar

Added an option as hiding sidebar in slide.
Also, it was changed to forcibly hide when outputting as PDF.

webpack

Fixed resolveLoader.module and resolve.modules.

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Thanks

Huge thanks to @saadq and @hiloki!