Encrypted config (#2)

* Add "FromEmail" config.
Add Configuration menu.

* Add for for entering SMTP username and password.

* Encrypt the username/password in the config file.

* Implement decryption when sending email.
Hide buttons when configuring credentials.

* Get the default credentials from the config file for editing.

Dynamic buttons (#1)

* Add TOML support and variables for button label.

* Add events and name buttons more generally.

* Hook up events to onDomReady.

* Updates to make the message match the labels.

* Make the button calls generic.

Initial commit to public branch.