Add possibility to chose hdf5 backend for saving ids data

• Add imas_backend option to 2 functions
• Use imas_open_env_backend instead of imas_create_env

matlab/TCV_IMAS/ids2database.m

-function [ids_put_status] = ids2database(shot,run,occurence,ids2put,tree_user,tree_tokamak,tree_majorversion,varargin);
+function [ids_put_status] = ids2database(shot,run,occurence,ids2put,tree_user,tree_tokamak,tree_majorversion,imas_backend,varargin);
 %
 %   [ids_put_status] = ids2database(shot,run,occurence,ids2put,varargin);
 %
@@ -7,6 +7,7 @@ function [ids_put_status] = ids2database(shot,run,occurence,ids2put,tree_user,tr
 % tree_name: getenv('USER') by default, can be 'public'
 % tree_tokamak: 'tcv' by default
 % tree_majorversion: '3' by default
+% imas_backend: "MDSplus" or "HDF5"
 %
 % varargin{1}: tbd
 %
@@ -16,6 +17,7 @@ ids_put_status = 0;
 tree_user_default = getenv('USER');
 tree_tokamak_default = 'tcv';
 tree_majorversion_default = '3';
+imas_backend_default = 'MDSplus';
 
 % initialize input parser
 p = inputParser;
@@ -28,6 +30,7 @@ p.addOptional('ids2put', struct([]), @(x) (isstruct(x)));
 p.addOptional('tree_user', tree_user_default, @(x) (isempty(x) || ischar(x)));
 p.addOptional('tree_tokamak', tree_tokamak_default, @(x) (isempty(x) || ischar(x)));
 p.addOptional('tree_majorversion', tree_majorversion_default, @(x) (ischar(x)));
+p.addOptional('imas_backend', imas_backend_default, @(x) (isempty(x) || ischar(x)));
 
 p.parse;
 defaults_ids2database = p.Results; % to keep track of defaults
@@ -53,8 +56,11 @@ elseif nargin==6
 elseif nargin==7
   p.parse(shot,run,occurence,ids2put,tree_user,tree_tokamak,tree_majorversion);
   params = p.Results;
-elseif nargin>=8
-  p.parse(shot,run,occurence,ids2put,tree_user,tree_tokamak,tree_majorversion,varargin{:});
+elseif nargin==8
+  p.parse(shot,run,occurence,ids2put,tree_user,tree_tokamak,tree_majorversion,imas_backend);
+  params = p.Results;
+elseif nargin>=9
+  p.parse(shot,run,occurence,ids2put,tree_user,tree_tokamak,tree_majorversion,imas_backend,varargin{:});
   params = p.Results;
 else
   p.parse;
@@ -100,6 +106,19 @@ if isempty(ids_names_ok)
   return
 end
 
+if ~ismember(params_ids2database.imas_backend, {'MDSplus', 'HDF5'})
+    warning(['Unknown imas_backend: ', imas_backend, ', selecting default: ',imas_backend_default]);
+    params_ids2database.imas_backend = imas_backend_default;
+end
+
+% Get IMAS backend ID
+switch params_ids2database.imas_backend
+  case "HDF5"
+    backendid=13;
+  case "MDSplus"
+    backendid=12;
+end
+
 try
   %% Initialize the three
   shot_is_new = 1; % seems only create is ok even if does already exist
@@ -109,10 +128,9 @@ try
     shot_is_new = 0;
   end
   if shot_is_new
-    idx  = imas_create_env('ids',shot,run,0,0,params_ids2database.tree_user,params_ids2database.tree_tokamak, ...
-          params_ids2database.tree_majorversion); %
+    idx = imas_create_env_backend(shot, run, params_ids2database.tree_user,params_ids2database.tree_tokamak, params_ids2database.tree_majorversion, backendid)
   else
-    idx  = imas_open_env('ids',shot,run,params_ids2database.tree_user,params_ids2database.tree_tokamak,params_ids2database.tree_majorversion); %
+    idx  = imas_open_env_backend(shot,run,params_ids2database.tree_user,params_ids2database.tree_tokamak,params_ids2database.tree_majorversion,backendid); %
   end
 
   %% Put the field