Boot custom CSS, and put some base, standard css in its place.
Shame I did not start with fresh Bootstrap4, but oh well.
Some more templates could be made to make this less messy, which would
be good.
* Proposals forms now have a header panel
* Adds panels to the speaker forms
* Imports latest pinax accounts templates
* speakers/base and proposals/base now derive from utility_page.html
* Most login forms now derive from take flight themes
* Missed email_confirm
* More accounts bits
* Restructures login form
* Puts submit etc buttons inside fieldset borders
* Themes speaker_edit.html
* speaker_create now uses takeflight theme
* proposal_submit_kind now uses takeflight theme
* fixes bug in form_snippet
* Optimises proposals_submit_kind
* proposal_submit now uses wagtail theme
* Proposal_edit now uses new theme
* More forms
* Proposal details page now loads from take flight theme
* proposal_fields now looks nicer under the take flight theme
* proposal_speaker_manage rethemed
