Keyboard shortcuts are added via a CodeMirror.keyMaps entry.
In literate mode (snippets), PgUp/PgDn are not bound, to allow scrolling.

More features and cleanup of project pane functionality.

'Init' does not create the document anymore. The client calls both
when it starts.

For batch compilation, compile with `Stm.VoDoc` type.
Terminate worker after batch finishes up.

Introduced a new command, 'Start', for use in multi-file compilation.

Mostly, to allow building in physical directories
(in subprocess mode).

In fact there was a typo in some dead code.

Lib.init() resets the global env. So all the flags etc. must be set after it.

Fixes #201.

[travis] Don't use incorrect git submodule call

This is updating not to the pinned module but to the remote, which
will make CI fail.

Travis should take care of the submodules already via

```
git:
  submodules: true
```

which IIANM is the default.

^^

Simplify the imports on the landing page

Docker script caused artifacts to still be built with OCaml 4.07.1.
Oops.

To keep up with Software Foundations, mainly.

Coq 8.12 has multi-char bullets (e.g. `--` or `***`).

Project Pane + nits

Fix CVE-2020-7660.

When building chunked packages using the CLI.

This precipitated some refactoing of package resolution code.
Also, while packages are loaded, a "wait" animation is shown in the
project toolbar.

(at last, yay ^^)

Brought over from v8.11+wacoq.