Add icons and declare e10s compatibility

v0.3.5

Declare e10s compatibility.

v0.3.4: Add a simple icon.

It’s most important that the button is visible.

v0.3.3: Fix CustomizableUI panel for new windows.

CustomizableUI.createWidget() should only be called once; the panel
is the only part that needs to be added to every window.

v0.3.2: Add `g` flag to host-matching regex.

It is very important.

v0.3.0

Block by default, with redirect and allow lists.

v0.2.1: Use CustomizableUI to create button.

This allows the button to retain both its position in its toolbar and its toolbar! Simple and impossible to find.

v0.2.0

The extensions.safeguard.whitelist preference is now reloaded automatically; the toolbar button toggles the current page’s host’s presence in that list.

v0.1.3

Click the button to reload the extensions.safeguard.whitelist space-separated list of domain names for which to allow http: as a scheme.

Known bugs:

• The button has no icon
• The button will retain its position, but always in the navigation bar; it can’t be removed