* improve Qt 5.6 support
* switch registry API to Windows XP compatible Unicode API
* update docs
* add comment for `CONFIG += c++14 c++17` in qmake .pro files
* fix logic for lockFile
* Arch Linux packaging; make LIBEXECDIR configurable
* update docs
* resolve libexec and share from relative path
* AppImage packaging
* allow build AppImage on Windows host