Less version 456

Version 456 was released on 8 Nov 2012.

These are the differences between version 451 and version 456:

• Allow backslash escaping of metacharacters in LESS environment variable.
• Don't quit if syntax errors are found in command line options.
• Increase sizes of some internal buffers.
• Fix configure bug with --with-regex=none.
• Fix crash with "stty rows 0".
• Fix Win32 attribute display bug.