Log Message:
yabasic: update to 2.86.2.

This fixes CVE-2019-19720.

Notable changes:

- Add dependency on devel/libffi
- Reset MAINTAINER, email address does not exist anymore
- Update LICENSE, Yabasic is now MIT licensed since version 2.77.1

ChangeLog:

Version 2.86.2 (December 12, 2019)
  - Another fix for heap-buffer-offerflow found with address sanitizer

Version 2.86.1 (December 8, 2019)
  - Fix for heap-buffer-offerflow

Version 2.86.0 (November 28, 2019)
  - Added new functions bitnot
  - Fixes for bit-arithmetic (signes/unsigned)

Version 2.85.0 (November 16, 2019)
  - Added new functions shl, shr and round
  - Introduced binary literals preceeded by 0b
  - Fixes for hex literals
  - The error-command no longer adds a line number

Version 2.84.3 (November 3, 2019)
  - Better debugging for library path
  - Clean builds for Windows setup-program

Version 2.84.2 (October 6, 2019)
  - Fixed some potential stackoverflows
  - Removed empty dir related with nano
  - Tests with tmux only within the Rakefile

Version 2.84.1 (July 20, 2019)
  - Make unload_library after call the default for foreign_functions
  - Fixes to docu
  - Requiring libffi for build (unless specified other by configure-option)
  - explicit error no longer unwinds call-stack

Version 2.84.0 (July 12, 2019)
  - New command foreign_buffer_set_buffer

Version 2.83.3 (June 30, 2019)
  - Documentation

Version 2.83.2 (June 30, 2019)
  - Allow specifying null-pointer for foreign functions

Version 2.83.1 (June 26, 2019)
  - Fix for line-numbers in errors after import
  - Updating the manual

Version 2.83.0 (April 29, 2019)
  - Unix: Added a syntax-file for the nano-editor;
    contributed by Stephan Muesse
  - Made parentheses around condition in while and until optional
  - Better error messages on misaligned control structures
  - New family of functions and commands foreign_* to invoke functions
    from external c-libraries
  - Fixes for line-numbers in error messages
  - Revised and updated the documentation

Version 2.82.1 (March 11, 2019)
  - Allowing comments after import statement
  - Fixes regarding error messages

Version 2.82.0 (February 17, 2019)
  - Advanced version of autoconf and other tools
  - Fix in tests
  - Fixed nested import of libraries
  - Libraries can now be found in the directory of the main file too
  - Error messages try to show and mark the offending part of the code
  - Hexadecimal numerical literals are supported, e.g. print 0xff

Version 2.81.4 (January 27, 2019)
  - Fixed error with inkey$ and clear screen
  - Fixed fatal error with inkey$ and upper case letters

Version 2.81.3 (January 13, 2019)
  - Fixed a compile-problem on macos
  - Corrected a rendering problem on www.yabasic.de, which had cut off the
    bottom-lines of many pages

Version 2.81.2 (January 2, 2019)
  - Fixed a problem under netbsd, which prevented yabasic from finding
    its own executable
  - Fix on macos for curses-initialization e.g. during "clear screen"
  - Fix that allows libraries to start with a comment introduced by
    a hash or a single quote
  - Made the prior "Guide into the guts" available again as "Some
    remarks on changing Yabasic"; see www.yabasic.de
  - Document options for unix and windows in the same chapter

Version 2.81.1 (November 1, 2018)
  - Fix: Allow yabasic to run from within a script

Version 2.81.0 (October 27, 2018)
  - New function chomp$
  - Added new peek "interpreter_path"
  - Fixed a sporadic issue with bound programs

Version 2.80.0 (September 8, 2018)
  - Added functions floor() and ceil()
  - Checking for function clock_gettime during configure