Describe the bug

Emoji marker display works out of the box, and normally emojis are displayed correctly, with most taking up the width of 2 ASCII characters each (I'm on GNU bash, version 5.0.16(1)-release (x86_64-apple-darwin17.7.0)).

However, when the marker column of a report contains emoji markers but no ASCII-markers (or column header label) wider than 1 character, then the required column width is incorrectly calculated to be 1 character wide, which does not leave enough space for the emoji markers to be displayed.

(I've only tested this on a small number of emojis but presumably the bug also applies to all other non-width-1 Unicode characters/symbols.)

To Reproduce

Open any report using the following marker config

[marker]
enabled = True
header_label=
require_color = False
# just override all (multi-character) defaults with a single emoji to be able to reproduce the bug on most reports
active.label =💡
blocked.label =💡
blocking.label =💡
completed.label =💡
deleted.label =💡
due.label =💡
#due.today.label =💡
keyword.label =💡
overdue.label =💡
project.label =💡
project.none.label =💡
recurring.label =💡
scheduled.label =💡
tag.label =💡
tag.none.label =💡

Expected behavior

Emoji markers should be displayed by allocating a wide enough marker column based on a correct calculation of the marker width (which might have to take into account properties of the console/font set).

Suggested fix

The mis-calculation happens in line 38 here, which assumes that every String character is exactly one display character wide:

Python-Curses doesn't seem to provide a way to perform a correct width calculation of Unicode symbols, so solving this might require recourse to an external library dependency (in particular https://github.com/jquast/wcwidth)