Changelog:
- main_loop.c (exec_global): Make commands 'q' and 'Q' work in a global command
- main.c: New option '-E, --extended-regexp'
- io.c (read_stream_line, write_stream): Add filename parameter. Print the file name in case of error
- global.c: Integrate 'resize_line_buffer' into 'set_active_node'
- buffer.c: Integrate 'resize_undo_buffer' into 'push_undo_atom'