Markdown: Tour Stop Implementation

Added Markdown help and hints to tour stop editing panel. Also changed
Markdown editor inputs (not rendering) to be monospaced so can support
features such as table layout.
Merge branch 'markdown' of git://github.com/NeilCresswell/ChronoZoom into NeilCresswell-markdown
Merge branch 'NeilCresswell-markdown'
Merge branch 'master' into production