Grids demos/SCSS: Added support for, and examples of external mailto: links.
Session: usability improvements to timeout message (#3190)

1. Simplified session timeout message to make it easier to understand.
2. Increased default inactivity time to 3 minutes.
Merge pull request #3335 from patheard/session-timeout

Session: usability improvements to timeout message
Merge pull request #3284 from EricDunsworth/v3.0-grids-icon-combos

Grids demos/SCSS: Added support for, and examples of external mailto: li...
Resolved merge conflicts