Add support for the XDG Base Directory Specification

[cmplstofB]

According to XDG Base Directory Specification by freedesktop.org, user configuration files for FVWM3 ought to be stored under $XDG_CONFIG_HOME/fvwm3 directory. (e.g. ~/.config/fvwm3/config.fvwm)

Currently, the default configuration files are stored under ~/.fvwm directory, and FVWM3 does not recognize the files under $XDG_CONFIG_HOME/fvwm3 directory.

I propose that the configuration files for FVWM3 are stored under $XDG_CONFIG_HOME/fvwm3 directory, not ~/.fvwm.

[ThomasAdam]

Thank you. But, no. Symlink this if you need it.