add FileSystem::TouchFile()
style/nlc
allow recursive expansion of paths in DataDirLocater::SubstEnvVars()
example:
"${XDG_CONFIG_HOME-\"~/.config\"}/spring"
"~/.config/spring"
"/home/user/.config/spring"
split DataDirLocater::Check() from DataDirLocater::LocateDataDirs()
ConfigHandler: use configfiles from all DataDirs
note: ~/.springrc & C:\Users\USER\AppData\Local\springsettings.cfg are now redundant cfg sources
Spring will now always save to the one in the datadir with write-access
Unix: make ~/.spring readonly and use ~/.config/spring instead