Homepage improvements

[bloqhead]

Homepage revisions

• spacing reduced in upper sections
• placeholder image added to the masthead where a GUI screenshot will go (we will need a GUI screenshot that shows charts and data to replace the placeholder image currently here)
• combined the 2 testimonials into a carousel further up on the page
• organized testimonials into the frontmatter section of the homepage markdown file

Unrelated fixes/improvements

• improved the dev script to eliminate random crashes due to VuePress memory usage (see #1819 in the VuePress repo)
• fixed a spacing issue on a tiny breakpoint range for the main navigation

[bloqhead]

@subnetmarco fixed the build error and launched. It was the carousel plugin I was using. I tried 4 separate ones before I found one that played well with VuePress' build process and SSR. Build error is completely gone now and no warnings either.