[MATLAB] Added utility function to add data directories

to Cantera's search path.
Pass Cantera error text as a format argument instead
of a format string to avoid issues with percent signs
and backslashes in error messages.

Author: ssun30

interfaces/matlab/+ct/+impl/call.m

@@ -7,7 +7,7 @@
     output = double(output);
 
     if ismember(output, ct.impl.errorCode)
-        error('Cantera:ctError', ct.impl.getError());
+        error('Cantera:ctError', '%s', ct.impl.getError());
     end
 
 end

interfaces/matlab/+ct/+impl/getArray.m

@@ -17,7 +17,7 @@
 
     iok = double(iok);
     if ismember(iok, ct.impl.errorCode)
-        error('Cantera:ctError', ct.impl.getError());
+        error('Cantera:ctError', '%s', ct.impl.getError());
     end
 
     % Convert output to double for better data compatibility

interfaces/matlab/+ct/+impl/getString.m

@@ -15,12 +15,12 @@
             error('not implemented - argument list contains more than one char array.')
         end
     else
-        error('Cantera:ctError', ct.impl.getError());
+        error('Cantera:ctError', '%s', ct.impl.getError());
     end
 
     iok = double(iok);
     if ismember(iok, ct.impl.errorCode)
-        error('Cantera:ctError', ct.impl.getError());
+        error('Cantera:ctError', '%s', ct.impl.getError());
     end
 
     % Discard the last character

interfaces/matlab/Utility/+ct/addDataDirectories.m

@@ -0,0 +1,22 @@
+function addDataDirectories(dirs)
+    % Add one or more directories to the data file search path. ::
+    %
+    %     >> ct.addDataDirectories('/path/to/data')
+    %     >> ct.addDataDirectories(["/path/one", "/path/two"])
+    %
+    % Directories are added to the front of the Cantera data file search path,
+    % so the most recently added directory is searched first. Use
+    % :mat:func:`dataDirectories` to inspect the current search path.
+    %
+    % :param dirs:
+    %     A string, char array, or string array of directories to add to the
+    %     Cantera data file search path.
+    arguments
+        dirs (1,:) string
+    end
+
+    ct.isLoaded(true);
+    for d = dirs
+        ct.impl.call('mCt_addDataDirectory', char(d));
+    end
+end