FlowTableWithFields: Replace the use of Gtk::Alignment.
Replace use of (deprecated) GtkLabel alignment.
Disable long-long warnings because Python uses long long.
configure.ac: Don't use -pedantic with the C sources.

Because the latest gcc doesn't like the object<->function-pointer
casts in eggmarshalers.c.
Operator UI: Replace most uses of GtkAlignment in Glade files.