* make sure all standard (eg. $CFLAGS) variables are taken into
account when compiling;
* define default compilation flags in separate $MAINT_* variables
so that user-defined variables can override them;
* split default flags the expected way, eg. $CPPFLAGS instead of
$CFLAGS for C preprocessor flags;
* declare all dependencies, including the ones on header files;
* install localized man pages in the corresponding locale-qualified
directories, so that man(1) can pick them up automatically;
* install .desktop file;
* support $DESTDIR for downstream maintainers' convenience;
* provide uninstall target;
* get rid of symlink hackery.