ui: added secondary action instead of two buttons on files page. - also made improvements for secondary dropdown actions in pull-requests

emails: added logic to allow overwriting the default email titles via rcextensions.

emails: set References header for threading in mail user agents even with different subjects - drop template headers() function as it wasn't used, and actually had bad implementation

diff-navigation: small improvements on text and display of navigation menu.

comments: added rcextensions hoooks for comment editing, and renamed methods to remove odd log_ prefix which isn't exactly what those functions were actually doing.

comments: added new events for comment editing to handle them in integrations.

comments-api: make edit API resilent to bad version data.

ui: fixed close button padding on toast messages.

diffs: added diff navigation to improve UX when browisng the full context diffs.

api: added get_comment method, and return versions for comments to allow simple edits via API.