Newline and tab ignored in echo

[thehans]

This used to work to insert a newline and tab in the GUI Console:

echo("Hello\n\tWorld!");

but looks like it got changed by 28d4a934

Previously "ECHO:" messages were specifically added using QPlainTextEdit::appendPlainText so that newline and tab could work, but now all console messages are added with QPlainTextEdit::appendHtml which ignores whitespace.

appendHtml is needed for Warnings etc which use the html to color the text.
But since echo strings get html escaped (so <br> can't be used either), there's no way to print multiple lines from one echo.

[TLC123]

Similar with:
echo( 1 , chr( 9 ) , 1 , chr( 13) , 1 );
-> ECHO: 1, " ", 1, " ", 1

echo(str( " 1 " , chr( 9 ) , 1 , chr( 13) , 1) );
-> ECHO: " 1 1 1"

in version 2020.12.31.ci6564 (git 7618d4d)