nano: Update to 5.7

nano: Update to 5.7

- Update from 5.6 to 5.7
- Update of rootfile not required
- Changelog
   Changes between v5.6.1 and v5.7:
      build: drop the check for two functions that we don't use any more
      build: fix compilation for --enable-tiny plus --enable-multibuffer
      build: fix compilation when configured with --disable-multibuffer
      build: fix compilation when configured with --enable-tiny
      bump version numbers and add a news item for the 5.7 release
      chars: implement mblen() ourselves, for efficiency
      chars: implement mbtowc() ourselves, for more efficiency
      chars: work around a UTF-8 bug in glibc, to display invalid codes right
      chars: work around the wrong private-use-character widths on OpenBSD
      display: avoid determining twice from and until where to draw each row
      display: make the output of --constantshow less jittery
      editing: prevent the pointer for the top row from becoming dangling
      feedback: upon first switch to a buffer, show its error message (if any)
      files: always register the format, also when the file is unwritable
      files: create a new buffer earlier, so that error messages can be stored
      files: when Mac format has been detected, stay with it
      gnulib: pull in the fix for a build problem on older Debian
      gnulib: update to its current upstream state
      indicator: adjust the size to the number of visible lines, not chunks
      input: accept Unicode codes for non-characters as valid, since they are
      memory: do not allocate space for multidata when it's already allocated
      memory: fix an off-by-one error to free also the last line in a group
      memory: prevent a use-after-free when the user respects a lock file
      oops: that doesn't work -- you can't break out of two for loops at once
      options: retire the obsolete 'smooth', 'morespace', and 'nopauses'
      softwrap: avoid time-consuming computations, to burden large files less
      startup: do not crash when trying to open a device or directory
      startup: do not store an error message in the record of another buffer
      startup: save the compiled file-matching regexes, to avoid recompiling
      startup: show the helpful message only when ^G has not been rebound
      syntax: c: colorize also labels that contain digits, and uncolorize colon
      syntax: po: improve the coloring of format specifiers
      syntaxes: replace [[:space:]] with [[:blank:]] to exclude carriage return
      tweaks: adjust and improve one comment, and frob another
      tweaks: adjust two comments, and reshuffle two fragments
      tweaks: avoid a warning on newer compilers, by writing an extra byte
      tweaks: avoid calling extra_chunks_in() when not softwrapping
      tweaks: avoid converting a file name for more than will fit on screen
      tweaks: avoid parsing a multibyte character twice
      tweaks: condense three comments, drop another, and rewrap a line
      tweaks: drop unneeded braces and adjust indentation after previous change
      tweaks: elide a call of strlen() for every row
      tweaks: elide a function that is now basically just two lines
      tweaks: elide an unneeded resetting NULL call to wctomb()
      tweaks: elide a small function that is used just once
      tweaks: elide the pointless is_valid_unicode() function
      tweaks: elide two more instances of useless character copying
      tweaks: improve a couple of comments
      tweaks: morph a function into what it is actually used for
      tweaks: normalize the indentation after an earlier change
      tweaks: put the most likely condition first, for a quicker return
      tweaks: reduce the maximum character length from six bytes to four
      tweaks: remove a misplaced (and nested) #ifdef
      tweaks: rename a variable, away from an abbreviation
      tweaks: rename a variable, for contrast with another
      tweaks: reshuffle a comment, and put the main extension first
      tweaks: reshuffle a fragment of code, to prepare for the next change
      tweaks: reshuffle two conditions, to have the most unlikely one first
      tweaks: set the file format only when unset, so it doesn't need saving
      tweaks: shorten a comment and trim an #ifdef
      tweaks: simplify two fragments of code
      tweaks: simplify two fragments of code, eliding useless character copying
      syntax: c: make the highlighting of '#include <...>' more compliant
      syntax: tcl: support Expect scripts too
   Changes between v5.6 and v5.6.1:
      bump version numbers and add a news item for the 5.6.1 release
      options: rename 'highlightcolor' to the more distinct 'spotlightcolor'
      search: correctly colorize a match also when softwrapping is active
      tweaks: rename a symbol, to better match the corresponding option

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>