Fixes:

• Solved crash when undoing chat input with ctrl-z (@siburec) ()
• groups: load group topics from Tox save ()
• Fix heap-use-after-free when creating new group chats (@siburec) ()
• langs: Remove strings that are not supposed to be translated ()
• Use correct type for pthread entry point (@krobelus) ()
• Pass enum value with correct type when cancelling file transfers (@krobelus) ()
• Copy text from chat without nicks via ctrl-c in Windows (@redmanmale) () Documentation:
• README.md: Add Spanish to the list of complete translations ()
• Add Debian installation instructions (@garetethan) ()
• docs: fix simple typo, precomplied -> precompiled (@timgates42) () Languages:
• Complete Spanish translation (@siburec) () Development:
• edit_do(): rename variable new to new_change ()
• edit_do(): remove useless variable history ()
• CI cleanup:
• add tools/timediff.py ()
• CI: OSX: Don't cleanup after installing with brew ()
• CI: OSX: Don't brew update ()
• CI: OSX: Install opus and lib{vpx,sodium} from brew ()
• CI: Win64: Don't install libopenal, it's already being compiled ()
• CI: Linux: Install lib{sodium,opus,vpx}-dev from repo ()
• rm extra/common/build_openal.sh ()
• Port Travis configuration to GitHub Actions (@krobelus) ()
• Disable -Werror for 3rd party projects (@krobelus) ()
• Require libsodium only when linking statically ()
• Remove libsodium dependency ()
• travis.yml: update OS to "focal" (latest) ()