Add support for Tab stop

[Groberen]

Is your feature request related to a problem? Please describe.
Tab stop, as done in Wordpad, Libre Office Writer, etc have this feature. Tab stop make the indention of text more predictable than some workarounds for some flustered methods of controlling character position.

As of today, for normal text - a similar function can be covered by using a table. But for many short lists, the use of a table are kind of overkill.

Regular, (multiple series of) tab can be used, but have the negative effect that the position of next word depends on the number of tabs, and also get ruined if the user afterwards decided to change the setting of tab width. Also, when copy this text from CT and pasting to another program, the tab/indentation get mangled and must be redone.

Using mono fonts may give the user the ability to control the indentation, but is a very rudimentary workaround because this forces the user to keep using mono font in all the text.

Describe the solution you'd like
Support for tab stops.

• User should be able to enable/disable tab stop.
• When tab stop are enabled, a ruler for tab stop should appear.
• Button and ability for the user to enable tab stop (for a selection of text).
• Tab stop ruler must behave the same as Libre Office Writer (except that only the tab stops icons is needed as CT does not use page margins like a regular document editor does).
• In cursor is placed within a list, I suggest that Ctrl+Tab make "insert tab to next tab stop" takes precedence over "toggle focus between tree and text".

[Groberen]

Another issue regarding adding multiple Tabs to force character Indent is that the indent aren't lined up when zooming (bigger/smaller characters) out/in - unless using mono fonr. Adding tab stop feature would neatly fix this issue.