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/libinterp/corefcn/utils.cc	Fri Apr 01 16:03:29 2016 -0700
+++ b/libinterp/corefcn/utils.cc	Fri Apr 01 18:16:01 2016 -0700
@@ -124,7 +124,7 @@
 %!assert (isvarname ("foo+bar"), false)
 
 %!error isvarname ()
-%!error isvarname ("foo", "bar");
+%!error isvarname ("foo", "bar")
 */
 
 // Return TRUE if F and G are both names for the same file.