Browser page parameters

The web build's page takes these query parameters:

http://HOST:PORT/?display=FILE.bob&macros=P=X,R=Y&zoom=1.5

parameter	meaning
`display`	the display to open, a path relative to the page or a URL (default `index.bob`); a URL on another server must allow cross-origin requests, and is refused when the page has a write token
`macros`	macros, `P=X,R=Y`
`zoom`	a fixed zoom factor instead of fitting the page
`pvws`	another PVWS server: `host[:port]` (meaning `wss://host[:port]/pvws/pv`, or `ws://` when the page is plain `http:` and the port isn't 443), or a full `ws://` or `wss://` URL; default `/pvws/pv` on the page's own server
`token`	the write token of a `bobview-server` started with `--write`; removed from the address once read

Without bobview-server

The web build (dist/web from scripts/build-web.sh, or share/bobview/web in a release) is a static site: serve it from any web server and point pvws at any PVWS server. The display's server must allow the page's origin (CORS) unless it is the same server.

Differences from the desktop

Displays have no windows of their own: every link navigates in place, and the pin and layout controls are not shown.
Images from PVA are not sent over PVWS yet.