sea: fix parameter name mapping

- rel_path = ['tm', '.', 'set'] should mean:

'tm': tm parameters first, with /<obj?/tm as main value
'.': then all parameters directly at top level, except 'set'
'set': all parameters  below 'set'
driving happens at object level

- better name mangling (the 1st appearance of the same shortname
  is kept short)

cfg/main/ma10high_t_cfg.py

@@ -22,7 +22,7 @@ Mod('tm',
     'frappy_psi.sea.SeaDrivable', '',
     io='sea_main',
     sea_object='tt',
-    rel_paths=['tm', 'set']
+    rel_paths=['tm', '.', 'set']
 )
 
 Mod('ts',