Fix reading the text ini file function get_ini_txt used in get_param_txt/set_param_txt

[plecharpent]

• The bug to fix is occurring when an ini file for a version > 10 does not contain parameters attached to snow module
• The STICS model take into account this lack in the ficini.txt reading considering they are optional
• But get_param_txt/set_param_txt are failing because the get_ini_txt is not considering snow parameters as optional
• This must be taken into account with using a version tag for identifying versions < 10 and >= 10
  for example in > 10 versions resperenne0 is replaced by restemp0