ftp.inc: FTP client implementation with socket connections

This class implements a client to access FTP server using TCP socket connections. It does not use any special FTP PHP extension.

Most of FTP commands are implemented by this class. It supports:

- Open FTP active and passive connections to a given server and port
- Authenticate as a given user or access with an anonymous login
- Can create, remove or change to a givem directory
- Query FTP server capabilities
- Execute the supported remote commands
- Retrieve directory listings
- Retrieve files from the beginning or resume downloads from a given position
- Delete, change permissions, or send files to the server
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