Allow custom characters for QTextOption ShowTabsAndSpaces

Summary

Allow custom characters for QTextOption ShowTabsAndSpaces.

Details

The current characters, (middle dot · 0x00B7 and rightwards arrow → 0x2192) are OK for denoting spaces and tabs. However, in some fonts, these characters are a little too pronounced, too visually distracting.

This suggestion is to allow the programmer to set the characters to something else instead of hard-coding the characters in qtextlayout.cpp.

I believe that this would allow for nice, custom-looking Qt-based text editors.

You can see my original StackOverflow question on this topic here:
http://stackoverflow.com/q/30179676/1354930

Attached Items

The attached image is how these dots look in the Spyder (Python) IDE which uses PyQt4 and the Consolas font. In my opinion, these middle dot characters are too big and I'd prefer to use something like 0x02D1 ˑ.

Related QT Issues

This request is related to issue # QTBUG-11144 (make the pen color configurable for ShowTabsAndSpaces) as it also pertains to the display of these characters.