allow use of swig tags (e.g. import) from markdown content files
allow data card macro to work with just url version: 'category/name'
include example of using data card macro in stratmap.md
add min-height to catalog images carousel, for pages with missing images
Merge remote-tracking branch 'origin/catalogImages'

Conflicts:
	templates/data-catalog.html
fix data catalog: add missing macro import
when converting things to urls, trim spaces first
automatically generate data catalog image urls
- based on standard naming convention and whether or not files exist
added thumbs and changed names
Merge branch 'master' into catalogImages