Improve the right-to-left/BiDi support of katePart:
The direction of each line is detected automatically, by the count of LTR/RTL chars in that string, and RTL lines will be automatically alligned to the right.

This patch is a work in progress, and I still need to fix some things:
* cursor movement in RTL paragraphs is still wrong
* when resizsing the window RTL paragraphs are not re-aligned, I think an internal redraw is needed.
* let the user specify the direction of the line manually, since this algorithm will fail some times.
* when LRM, RLE and all those chars are in the beginning of the line - obey that direction, and ignore all others.
* make a visual hint (like tabs or spaces?) for special invisible BiDi chars.
* this works pretty good in kwrite, but in kate it behaves funny, need to test this much more.
* more testing :)