Stop beginning of unindent() selection from travelling into prev line
Stop beginning of unindent() selection from travelling into prev line

The new behavior matches Ace Editor.  However another
common semantics, used by at least Kate and Geany, is
to always make the resulting selection start from
the beginning of the first line.  Geany (unlike Kate)
also adjusts the *end* of the selection to include
all of its ending line.  I chose the Ace behavior as
one that is the smallest behavior change from existing
bililiteRange behavior, not because I have a preference.

dwachss/bililiteRange,dwachss/bililiteRange