Rename: groupchats -> conferences

This is in line with the toxcore API naming scheme and is in preparation
for the merge with the new groupchat implementation

Makefile

@@ -14,7 +14,7 @@ LDFLAGS ?=
 LDFLAGS += ${USER_LDFLAGS}
 
 OBJ = autocomplete.o avatars.o bootstrap.o chat.o chat_commands.o configdir.o curl_util.o execute.o
-OBJ += file_transfers.o friendlist.o global_commands.o group_commands.o groupchat.o help.o input.o
+OBJ += file_transfers.o friendlist.o global_commands.o conference_commands.o conference.o help.o input.o
 OBJ += line_info.o log.o message_queue.o misc_tools.o name_lookup.o notify.o prompt.o qr_code.o settings.o
 OBJ += term_mplex.o toxic.o toxic_strings.o windows.o