Changes error macros. Value 0 will be reserved for the case where there is no error message
Moved register code into separate function
Linked list library to client_PFS
Added 'ls' command
Added request_file_list method
Added threads to wait for server requests and listen for get requests
Added address pointer cast in accept call
Added bug to problems list
Added toreceive method
Clients can now send and receive get request from each other (but they don't send responses)
Added rules for test directories
Clients can now get actual data from each other