Feature Request: Tab char should be dynamically sized and align colums

[preiter93]

See this discussion
#14 (comment)

Currently edtui interprets tabs as X spaces, while most other editors visually align the columns.
For example, for a tab_width of 2, a space + tab will take up 3 cells in edtui, whereas it should only take up 2 cells.
The displayed width should always be a multiple of 2 in this case.