AltCopy wót Max Nikulin

A helper to copy link title, "alt" image description, full timestamp, etc.

Developer tools are certainly more powerful when some text can not be selected directly but they are less convenient in some frequent cases. In addition to "title" and "alt" attributes, the following properties are tried:
- chosen option of <select> element,
- value of <input> form element that is suitable for date, time, color, range, etc. or its placeholder,
- text of an element when selection is suppressed through CSS,
- selected text, link target, or image source if nothing "better" is available.

Grant the notification permission in the add-on manager to be aware of failures to extract or to copy text.

The clipboard permission in add-on preferences makes copy action more reliable in Firefox-102 ESR,

Due to the browser security policy the add-on features are rather limited on privileged sites including addons.mozilla.org, for PDF files, etc.

See the project page for more details.