maint: Follow Octave conventions for use of semicolon in BIST tests. * testfun.txi: Document Octave conventions for use of semicolon in BIST tests. * cellfun.cc, ellipj.cc, file-io.cc, gcd.cc, hash.cc, nproc.cc, utils.cc, fftw.cc, ov-usr-fcn.cc, oct-parse.in.yy, md5sum.m, wavread.m, wavwrite.m, cplxpair.m, rat.m, im2double.m, rref.m, stem3.m, rotate.m, pchip.m, blackman.m, hamming.m, hanning.m, spectral_adf.m, spectral_xdf.m, assert.m, fail.m, etime.m, build-sparse-tests.sh, classes.tst, ctor-vs-method.tst, index.tst, io.tst, struct.tst: Follow Octave conventions for use of semicolon in BIST tests.

--- a/scripts/time/etime.m	Fri Apr 01 16:03:29 2016 -0700
+++ b/scripts/time/etime.m	Fri Apr 01 18:16:01 2016 -0700
@@ -75,7 +75,7 @@
 %! assert (etime (t5, t1), 13);
 
 ## Test input validation
-%!error etime ();
-%!error etime (1);
-%!error etime (1, 2, 3);
+%!error etime ()
+%!error etime (1)
+%!error etime (1, 2, 3)