Table → Text-0.2.0
[+] Horizontal alignment taken into account
[+] Custom symbols can be chosen instead of "-","+","|".
[x] New tables are placed in a new document
[+] Ability to convert all tables of the document at once (when no table is specified)
Remaining issue:
on Windows, when a cell has more than one line of text, there are redundant paragraphs that have to be replaced by spaces manually.