Improve printed schedule

Show each day on a new page when printed.
Hide elements that do not assist with printed copy (current time, etc).

Styling for schedule

Update to Bootstrap 4 throughout.
Remove unused blocks and elements from past conferences.
Ensure schedule works in print mode.

Finalise registration

Add shirt types and sizes. Improve messaging about discounts.
Restyle ticket wizard and product category screens. Enable page titles
and messages. Update dashboard to hide raffle.
Enable inventory population for dev container.

Improve proposal/review styling

Use correct block for page titles. Fix element styles to be consistent
across site. Use fluid layout for review to enable sidebar.

Switch to LCA2020

Remove LCA2018 and LCA2019 styles and content.
Add base LCA2020 styling and update references to year.

Fix padding for schedule

Add column to layout so mobile has padding. Use container to wrap schedule so padding and
centred table applies to all views.

Use more real estate on xl screens

Prior to this change, on a screem >1200px wide the .container was
capped at 1140px, which leaves a lot of whitespace.

This increases the cap to 1900px, more effectively using
larger screens while still preventing the text from getting so
wide as to be hard to read.

Partial fix for #109

Fix notification styling

Fixes #88