Less version 557

Version 557 was released on 28 Mar 2020.

These are the differences between version 551 and version 557:

• Update Unicode tables.
• Treat Hangul Jamo medial vowels and final consonants as zero width.
• Display error message immediately when -o is toggled and input is not a pipe.
• Fix display bug in WIN32C version.
• Fix memory corruption when built with libtermcap.
• Support libtinfow.