added errors if sofa is not installed

applications/Binaural-HRTF/HRTF_class/@itaHRTF/itaHRTF.m

@@ -520,6 +520,10 @@ classdef  itaHRTF < itaAudio
             
             
             function this = set.sofa2itaHRTF(this,pathFile)
+                %% check if sofa is installed
+                if ~exist('SOFAstart.m','file')
+                    error('SOFA not installed. Run ita_sofa_install');
+                end
                 if ~exist(pathFile,'file')
                     f=filesep;
                     pathFile=[SOFAdbPath f 'SOFA' f pathFile];

kernel/DataAudio_IO/ita_read/ita_read_sofa.m

@@ -26,6 +26,11 @@ else
 end
 
 
+%% check if sofa is installed
+if ~exist('SOFAstart.m','file')
+    error('SOFA not installed. Run ita_sofa_install');
+end
+
 
 %% Open the sofaFile
 

kernel/DataAudio_IO/ita_write/ita_write_sofa.m

@@ -52,6 +52,14 @@ userDataFields = {'GLOBAL_Conventions','GLOBAL_Version','GLOBAL_SOFAConventions'
     ,'EmitterPosition','EmitterPosition_Type','EmitterPosition_Units','RoomCornerA','RoomCornerA_Type','RoomCornerA_Units' ...
     ,'RoomCornerB','RoomCornerB_Type','RoomCornerB_Units'};
 
+
+%% check if sofa is installed
+if ~exist('SOFAstart.m','file')
+    error('SOFA not installed. Run ita_sofa_install');
+end
+
+%%
+
 switch(sArgs.dataType)
    
     case 'HRTF'