Fix regression with CJK wide chars at cursor
requested to merge ninjalj/konsole:work/ninjalj/fix-463031-cjk-double-wide-char-at-cursor into master
Commit 76f879cd changed greatly the way konsole renders text, to fix some long-standing issues with RTL text, non-monospaced fonts, ...
Unfortunately, it also introduced a regression for CJK wide character rendering, where it does not take properly into account their width.