core: add variable "old_full_name" in buffer, set during buffer renaming (issue weechat/weechat#1428)
core: add debug option "-d" in command /eval (issue weechat/weechat#1434)
api: add functions crypto_hash and crypto_hash_pbkdf2
api: add info "auto_connect" (issue weechat/weechat#1453)
api: add info "weechat_headless" (issue weechat/weechat#1433)
buflist: add pointer "window" in bar item evaluation
irc: add support of fake servers (no I/O, for testing purposes)
relay: accept hash of password in init command of weechat protocol with option "password_hash" (PBKDF2, SHA256, SHA512)
relay: reject client with weechat protocol if password or totp is received in init command but not set in WeeChat (issue weechat/weechat#1435)

core: fix memory leak in completion
core: flush stdout/stderr before forking in hook_process function (issue weechat/weechat#1441)
core: fix evaluation of condition with nested "if" (issue weechat/weechat#1434)
irc: split AUTHENTICATE message in 400-byte chunks (issue weechat/weechat#1459)
irc: copy temporary server flag in command /server copy
irc: add nick changes in the hotlist (except self nick change)
irc: case-insensitive comparison on incoming CTCP command, force upper case on CTCP replies (issue weechat/weechat#1439)
irc: fix memory leak when the channel topic is changed
logger: fix crash when logging is disabled on a buffer and the log file was deleted in the meanwhile, when option logger.file.info_lines is on (issue weechat/weechat#1444)
php: fix crash when loading script with PHP 7.4 (issue weechat/weechat#1452)
relay: update buffers synchronization when buffers are renamed (issue weechat/weechat#1428)
script: fix memory leak in read of script repository file if it has invalid content
script: fix unexpected display of scripts list in buffer with command /script list -i
xfer: send signal "xfer_ended" after the received file has been renamed (issue weechat/weechat#1438)

scripts: fix generation of test scripts with Python 3.8
unit: add tests on IRC protocol functions and callbacks
unit: add tests on function secure_derive_key
unit: add tests on functions util_get_time_diff and util_file_get_content

core: fix Cygwin build
guile: add detection of Guile 3.0.0 (issue weechat/weechat#1442)
irc: fix build with GnuTLS < 3.1.0 (issue weechat/weechat#1431)
php: add detection of PHP 7.4
ruby: add detection of Ruby 2.7 (issue weechat/weechat#1455)