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/sea/ma02.config.json

@@ -269,7 +269,7 @@
 {"path": "custompar", "type": "float", "readonly": false, "cmd": "hemot custompar"}]},
 
 "mf": {"base": "/mf", "params": [
-{"path": "", "type": "float", "kids": 26},
+{"path": "", "type": "float", "cmd": "run mf", "kids": 26},
 {"path": "persmode", "type": "int", "readonly": false, "cmd": "mf persmode"},
 {"path": "perswitch", "type": "int"},
 {"path": "nowait", "type": "int", "readonly": false, "cmd": "mf nowait"},