Implement server mode.

This new mode works by first loading the model then listening for TCP
connections on a port. When a connection is received, arguments will be
parsed using a simple protocol:

- First the number of arguments will be read followed by a newline
  character.
- Then each argument will be read, separated by the 0 byte.
- With this we build an argument vector, similar to what is passed to
  the program entry point. We pass this to gpt_params_parse.

Finally `run` will be executed with the input/output streams connected
to the socket.

Signed-off-by: Thiago Padilha <thiago@padilha.cc>

chat_tcp_client.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+PORT=${PORT:-8080}
+PROMPT="${PROMPT:-"Transcript of a dialog, where the User interacts with an Assistant named Bob. Bob is helpful, kind, honest, good at writing, and never fails to answer the User's requests immediately and with precision.
+
+User:Hello, Bob.
+Bob:Hello. How may I help you today?
+User:Please tell me the largest city in Europe.
+Bob:Sure. The largest city in Europe is Moscow, the capital of Russia.
+User:"}"
+RPROMPT="${RPROMPT:-"User:"}"
+N_PREDICT="${N_PREDICT:-"4096"}"
+REPEAT_PENALTY="${REPEAT_PENALTY:-"1.0"}"
+N_THREADS="${N_THREADS:-"4"}"
+
+# Open connection to the chat server
+exec 3<>/dev/tcp/127.0.0.1/${PORT}
+
+# Pass the arguments. The protocol is really simple:
+# 1. Pass the number of arguments followed by a linefeed
+# 2. Pass the arguments, with each being followed by "0"
+(
+echo -en "12\n"
+echo -en "-t\x00"
+echo -en "$N_THREADS\x00"
+echo -en "-n\x00"
+echo -en "$N_PREDICT\x00"
+echo -en "--repeat_penalty\x00"
+echo -en "$REPEAT_PENALTY\x00"
+echo -en "--color\x00"
+echo -en "-i\x00"
+echo -en "-r\x00"
+echo -en "$RPROMPT\x00"
+echo -en "-p\x00"
+echo -en "$PROMPT\x00"
+) >&3
+
+trap exit TERM
+
+# When we have passed the arguments, start printing socket data to the screen.
+# This is done in a background job because we also want to send data when
+# running in interactive mode.
+cat <&3 && echo "(disconnected, press \"enter\" twice to exit)" &
+cat >&3
+wait