#43 selecting text with shft-right arrow

[Vittorio]

When a select some text with shft-right arrow the selection increases by 2 characters at the time. It works as expected with shft-left arrow.

[Bernard Desgraupes]

There was indeed a position off by 1 in the -[extendSelectionToPos] method.This is fixed now.

Changes committed to svn (rev. 1086). The core must be rebuilt.