documented ftp clients support
replaced LICENSE with text of GPLv3
use read(2) instead of mmap(2)

This changes allow to get data from not regular files only but from
pipes, sockets, devices.
added stdin support

If FILE option is omitted the stdin is used for reading. This allows
to use the next scenarios:

	1. ls --color=never -lR | ls-fuse ~/mnt
	2. ls-fuse ~/mnt < file.ls-lR
	3. ls-fuse ~/mnt # and type from keyboard