Integrate Smartdown with the impress.js presentation library. The basic idea is that a set of Smartdown docs can be assembled into a presentation. Impress.js slide attributes can be specified in index.html or in the frontmatter of the Smartdown documents.

The idea is to move as much of the specification of the ordering of content and the content itself from the realm of index.html into the more comfortable Markdown format, including Markdown frontmatter. So basically, an impress.js slideshow that would ordinarily be specified in an index.html can instead refer to a Manifest.md file by adding a slide definition like the following to index.html:

  <div
    id="manifest"
    class="step slide smartdown manifest"
    src="./Manifest.md"
  >
  </div>

The contents of Manifest.md will typically be only Markdown frontmatter (YAML). The important part is the files: section, which lists the Markdown (or Smartdown) files to be rendered as slides. The exampleBasic/Manifest.md file looks like this:

---
impress:
  data-x: 1000
  data-y: 1000
  files:
    - ./Overview.md
    - ./Home.md
    - ./Multi.md
---

Smartdown supports a feature called Multicards which enables an author to put the text for multiple Smartdown cards in a single file. For example, the following Smartdown text will be displayed as three separate cards in an ordinary Smartdown viewer. However, smartdown/impress will create three separate slides.

 Apple
 ---

### All about Apples

Apples are sometimes red.

 Cherry
 ---

### All about Cherries

Cherries are sometimes red.

 Book
 ---

### All about Books

Book are sometimes read.

0.0.1 - Initial attempt at integrating Smartdown with Impress.js, including three examples. Requires Smartdown 0.0.118+. Another contribution here is the use of Manifest.md files and their frontmatter to help authors avoid HTML. Allow Smartdown tunnel syntax to be used to navigate within a presentation. Examples include a Smartdown Gallery example that demonstrates and stress-tests some Smartdown features. The exampleBasic/ example provide a pages.html to view slides one at a time without Impress.js. 0.0.2 - Uses latest impress.js build. 0.0.3 - Use SD 1.0.2 and updated impress.js build. Add 'flatten=horizontal' and 'flatten=vertical' options to URL. Ensure that slides become visible only after their Smartdown is loaded. Eliminate the use of pages.html in favor of the flatten mode. Repurpose fallback message as a please-wait-for-loading message. Delete unused CSS files inherited from the original impress.js examples. Add start buttons to Overview.md for the examples.