Rendering.Render_HTML: fix additional bugs with unordered list handling

Fix alire.toml version number

Bump version to v14.prelease

Bump version to v13

Rendering.Render_HTML: render multiline unordered list items identically to single-line items

This fixes some minor issues with how multiline unordered list blocks were
treated distinctly and would, for instance, have <p></p> tags inside the
<li></li>, plus some non-significant whitespace differences.  Now multiline
list items are rendered identically to single-line list items (other than the
possibility of rendered markup)

Rendering.Render_HTML: fix bug with consecutive multiline list items

Fix bug where having consecutive multiline unordered list items would open a
new <ul> block and not properly close them.  Add test to ensure it doesn't
recur.

README: add note about prebuilt binaries

.builds: save artifacts from all scripts

.builds: generate build artifact for executable

Bump version to v13.prerelease

Bump version to v12

Gemroff: Add unordered list item blocks

This allows using inline markup inside of unordered list items, using standard
block syntax.

Rendering.Render_Gemtext: clean up escaping code

Rendering.Render_HTML: add option to lazy load images

Add lazy-load-images configuration option and change Render_HTML output to
add `loading="lazy"` attribute to inline images when set.

Bump version to v12.prerelease

Bump version to v11

Rendering.Render_Textual: hard wrap unordered list lines

gemroff, gemroff(1): add proper summary and include summary in `-h` output

Makefile: properly clean up all testing artifacts

README: add note about de facto standard Ada compiler