v0.8.12, build 174

Added an e-mail writing assistant.
Added the possibility to preselect some e-mail writing assistant options.
Improved the coding assistant by adding a button to delete a context.
Improved chat page by scrolling to the bottom after loading (configurable; default is on).
Improved all assistants to provide a button to copy their respective result to the clipboard.
Improved the content validation for the agenda assistant.
Improved the language handling of the agenda assistant.
Improved the chat options readability by separating the preselection of values.
Improved some default settings. Default key for sending input is now Enter. The default update check is now set to hourly. The navigation menu behavior is now set to use tooltips.
Refactored the "send to" implementation of assistants.