path_manager: use stable_sort() to keep original position
Trivial changes (typo,renamed)
entry_operation: implement default behaviors
Rename entry_operation to fs_operation
Implement experimental clone op

 This clone functionality is based on Plan 9 concept
But is not perfect now and TCP client and server operations
don't support it yet.
 Also installer operation is introduced for easier installation
of fs_operations.
Add a new http client example based on the new style
exception_errno: fix bug wrongly private-inheriting
planetfs_main: handle unknown exceptions
dir_op: log given path and support /ip
Create a new header for filesystem entry
Improve readability
Implement expermental ctl,data and session dir operations

 This implements Plan 9-based session management functions.
Now, client_op and server_op are alredy obsouted.
tcp: ctl: implement is_connected request

 To implement this we have to know the state of the socket.
As such a function is not provided by standard socket API,
we can get the socket information about TCP by using getsockopt()
with TCP_INFO even though that functionality depends on Linux
Kernel.
Improve regex
fs_core: open: handle return value of open operation
Implement experimental /tcp/*/remote operation

 Also introduce brand new file descriptor managing table
to implement sessions effectively
Implement /tcp/*/local operation
Fix .gitignore and typo and remove logs
Makefile: disable intr_signal option
More support for IPv6