Remove shadow for goto box
Update changelog, bump version
Fixes #79 with better key handling also in the project picker window, so
may contribute to fixing #80 as well.
More changelog
New Zed black theme
Big theming refactor, fixes #82

All themes are now managed by Zed itself and reside in the Configuration
project (see themes.json and /default/theme/*). So it's now possible to
create your themes from within Zed (although changes to the CSS will
require a reopening of the editor).

As a bonus: new custom Zed Dark theme, which is the default.

Existing users: your theme will be reset to "Zed Dark" initially since
the theme names changed.
Added more specific position information to jshint messages
(approximation) resulting in underlined identifiers.
On Mac with dark themes the text mouse cursor is barely visible,
therefore on dark themes and mac the default cursor is now used. Not a
great solution, but the best I could come up with.
Added README to configuration project
Fixes #65 by adding a `gotoExclude` preference an array with a simple
pattern language: the pattern should match the whole file path and you
can use * as a wildcard. For instance:

  "gotoExclude": ["/build/*", "*.bak", "*/dist/*]
Fixes #78 and reorganizes sandbox in general.

Moved code around, all sandbox APIs are now in the configuration
project, the implementations are still in js/sandbox.

Zed-specific files now start with `zed::` instead of `zed:` and appear
in the goto file list so you can always go to `zed::start` to find the
cheat sheet.

The sandbox now runs in a Chrome webview, which runs in a separate
process therefore no longer blocking the Zed UI thread.
Minor sandbo tweaks