maint: Use convention 'int& x' for naming references. * ButtonGroup.cc, Canvas.cc, Canvas.h, annotation-dialog.cc, annotation-dialog.h, dialog.h, documentation-dock-widget.cc, files-dock-widget.cc, files-dock-widget.h, find-files-dialog.cc, find-files-dialog.h, find-files-model.cc, find-files-model.h, history-dock-widget.cc, history-dock-widget.h, file-editor-tab.cc, file-editor-tab.h, file-editor.cc, file-editor.h, main-window.cc, main-window.h, octave-qt-link.h, parser.cc, parser.h, webinfo.cc, webinfo.h, settings-dialog.cc, bsxfun.cc, call-stack.cc, call-stack.h, fft.cc, fft2.cc, fftn.cc, gl-render.cc, graphics.cc, graphics.in.h, input.cc, load-save.cc, ls-hdf5.cc, ls-hdf5.h, octave-link.h, pr-output.cc, regexp.cc, sparse-xdiv.cc, sparse-xdiv.h, symtab.cc, xdiv.cc, xdiv.h, zfstream.h, __eigs__.cc, __ode15__.cc, ov-base.h, ov-builtin.cc, ov-cx-sparse.h, ov-fcn-handle.cc, ov-fcn-handle.h, ov.cc, ov.h, jit-ir.h, jit-typeinfo.cc, jit-typeinfo.h, pt-jit.cc, pt-jit.h, CMatrix.cc, CMatrix.h, CSparse.cc, CSparse.h, MatrixType.cc, MatrixType.h, dDiagMatrix.cc, dMatrix.cc, dMatrix.h, dSparse.cc, dSparse.h, fCMatrix.cc, fCMatrix.h, fDiagMatrix.cc, fMatrix.cc, fMatrix.h, eigs-base.cc, oct-fftw.cc, oct-rand.h, sparse-dmsolve.cc, kpse.cc, lo-regexp.h: Use convention 'int& x' for naming references.

--- a/libinterp/corefcn/regexp.cc	Mon Apr 24 14:38:34 2017 -0700
+++ b/libinterp/corefcn/regexp.cc	Mon Apr 24 17:20:37 2017 -0700
@@ -330,8 +330,8 @@
 }
 
 static octave_value_list
-octregexp (const octave_value_list &args, int nargout,
-           const std::string &who, bool case_insensitive = false)
+octregexp (const octave_value_list& args, int nargout,
+           const std::string& who, bool case_insensitive = false)
 {
   octave_value_list retval;
 
@@ -516,8 +516,8 @@
 }
 
 static octave_value_list
-octcellregexp (const octave_value_list &args, int nargout,
-               const std::string &who, bool case_insensitive = false)
+octcellregexp (const octave_value_list& args, int nargout,
+               const std::string& who, bool case_insensitive = false)
 {
   octave_value_list retval;
 
@@ -1281,7 +1281,7 @@
 */
 
 static octave_value
-octregexprep (const octave_value_list &args, const std::string &who)
+octregexprep (const octave_value_list& args, const std::string& who)
 {
   int nargin = args.length ();