Display line and column number in plain and code editors

[danielfernandez]

Displaying the current line and column number in a status bar is a basic feature in almost all text editors (and a required feature in code editors). This allows properly formatting documents, checking indentations, etc.

Ideally, when text is selected, the number of lines and columns currently selected should be displayed too.

Please add line and column display to both the "plain" and "code" editors.