Add support of single-line box drawing characters.
Add support of single-line box drawing characters.

liblouis/liblouis,hammera/liblouis,BueVest/liblouis,hammera/liblouis,BueVest/liblouis,BueVest/liblouis,hammera/liblouis,hammera/liblouis,liblouis/liblouis,hammera/liblouis,liblouis/liblouis,liblouis/liblouis,BueVest/liblouis,hammera/liblouis,BueVest/liblouis,liblouis/liblouis,liblouis/liblouis,BueVest/liblouis