Added the ability to include newlines in prefixes and suffixes.

Fixed an issue with copying the message ID for a message in its own tab (not in the 3-pane view).

Added visual feedback upon copying the message ID! A little popup box will briefly tell you what you copied, or if there was an error.

Version 1.2.0 adds a new option to copy the raw message-id. This means copying the message-id header and value as-is with exact casing and whitespace. For example, if the ID was:
MesSaGe-iD: <123@
email.com>

Without raw enabled the add-on would copy:
123@email.com

but with the option enabled you get:
MesSaGe-iD: <123@
email.com>"

The minimum supported version is now 68.7, but anyone who doesn't need raw copy and wants to stay on a lower version is not missing out on anything yet.

Adds an options page with the following options:
* prefix/suffix strings to append to the message ID
* Include the angle brackets around the message ID
* URL encode the message ID

Updates the add-on to use the newer WebExtension APIs. The add-on no longer requires a restart to enable. If it doesn't show up in your message display toolbar immediately, try right-clicking and selecting "Customize". If two buttons appear, try restarting Thunderbird.

Support Thunderbird 68.*