Less version 438

Version 438 was released on 31 Dec 2010.

These are the differences between version 436 and version 438:

• Add %F formatting to prompt strings, replaced by the last component of the input file.
• Less now exits with status 2 if control-C is pressed and -K is in effect.
• Fix "ungetc overflow" when passing long commands via the -p option.
• Fix bug in using line filtering via the & command in combination with -i and -I.
• Fix bug in handling negative arguments to the -j option.
• Fix bug in handling %t in prompt strings.
• Improve handling of long option names.
• Improve percentage calculation for very large files.