Better name for tmp file

 - Tmp file is now cached
 - Better extension
 - Update TODO

TODO.md

@@ -6,8 +6,7 @@
 
     + @RomFouq: Add message on reset
 
-## Master issue
- + Correct biniou extension in tmp file
+## Major issue
 
 ## Short term
 

src/const.ml

@@ -47,4 +47,4 @@ let home = match (Sys.getenv "HOME") with
 (* Some settings variales *)
 let rc_file = home ^ "/" ^ ".oclaunch_rc.json";;
 (* Set tmp file, in witch stock launches, in biniou format *)
-let tmp_file = "/tmp/oclaunch_trace.bi";; (* File where launch are logged *)
+let tmp_file = "/tmp/.oclaunch_trace.dat";; (* File where launch are logged *)