Handle right-trucation for ICU normalized terms.

Handle right-trucation for ICU normalized terms.

The string searches now handles right-trucation for ICU normalized terms.
That is @attr 5=1 is supported as well as no-truncation, @attr 5=100. All
other truncation attributes produces an error. We use some pretty heuristic
methods to determine where to put the .* in our resulting regular
expression.