Bug fixes:

• fixed possible integer overflow when reading a specially crafted packet
• fixed possible integer overflow in userauth_keyboard_interactive with a number of extremely long prompt strings
• fixed possible integer overflow if the server sent an extremely large number of keyboard prompts
• fixed possible out of bounds read when processing a specially crafted packet
• fixed possible integer overflow when receiving a specially crafted exit signal message channel packet
• fixed possible out of bounds read when receiving a specially crafted exit status message channel packet
• fixed possible zero byte allocation when reading a specially crafted SFTP packet
• fixed possible out of bounds reads when processing specially crafted SFTP packets
• fixed possible out of bounds reads in _libssh2_packet_require(v)