R7.0 bugfixes

• Removed fixed-width limitations on some plot and map templates
• Smartpanel removed 'New Layout' and 'New Display' from left menu (as user has 'New' card on Layouts / Displays pages)
• Smartpanel BusStopsChooser bugfix - trailing slash added to 'transport/stops/' API call

API release, portrait Smartpanels, code cleanup

• smartpanel 'displays map' page moved to 'displays list' + 'displays map', with list as the default for 'My displays'
• smartpanel various updates to displays lists to advertise the slug/URL for the display
• smartpanel layout config supports landscape/portrait with grid sizes 6x4 (as before)
  plus 9x6, 12x8, 'design' json changed from 'list of widget configs' to { grid: 'grid info', widgets: 'list of widget configs' }
• smartpanel template code layout/layout_config cleaned up so gridstack on layout_config and no gridster left on layout.
• smartpanel layout (i.e. display, not config) now dynamically resizes to fill screen, no 1920x1080 fixed size
• IframeArea widget adds X and Y offset parameters (in addition to url and scale)
• removed legacy code from transport app (urls, views, templates)
• deleted old-bus-map, removing legacy DataServer API dependency
• removed erroneous Zone link on main menu
• added ability to associate authorised referers with tokens
• requires authentication and rate throttling for access to the Transport API endpoints
  • requires T&C'ss agreement before accessing any of the API
• added setup_tfc_prod management command to set up API tokens for use by the tfc_web code, replacing the stand-alone script that just set TFC_WEB INTERNAL. Adds additional secrets.
• passes one of these tokens (TFC_WEB JS) into the SmartPanel code to authenticate access by widgets
  and by widget configuration to the transport API. In the process, implement an earlier proposal that
  all Django config items with names starting SMARTPANEL_ are passed to widgets in the settings
  object of their config parameter, and use this to also pass the URL of the API endpoint that widgets
  should use.
• significantly revised and hopefully improved the API documentation
• add front page links to the API (essentially releasing it to public)
• moved smartpanel static files into smartpanel/static/smartpanel
• modified Django templates to refer to common templates/base.html

Generalise SmartpanelUser into SmartCambridgeUser

Re-work existing code that manages terms and conditions fir the Smartpanel into something that can manage terms and conditions for other aspects of the platform.

Misc application platform changes

User-visible changes

• Add new traffic monitoring zones
• Add the ability to import and export SmartPanel definitions
• Increase the use of secure (https) connections on the platform
• Terms and Conditions for use of SmartPanels
• Improve links between the Traffic pages - add links to information about traffic flow in the other direction
• Added scale to traffic maps
• Fix a number of broken links to external web pages
• Fix a bug causing a large numbers of bogus connections from SmartPannel clients

Internal changes

• Create socketclient
• Add polygon creation to rtroute
• Add Data API
• Modify AQ/Parking/Traffic pages to use the data API
• Add transit distance and derived speed to zone completion messages
• Add zone completion and car park occupancy to the data available from rtmonitor
• Initial Ofo/Mobike widget