Fix checks for scalar multiplication to not have to stringify the val…

[dpvc]

Fix checks for scalar multiplication (for points, vectors, and matrices) to not have to stringify the value if it is already a Real or Complex number. This resolves bug 3991. The issue was that when Context()->texStrings is in effect, the string match that was used to decide if the coefficient is a number would match against the TeX version of the number. When the number is large enough for scientific notation (i.e., more than 6 digits), then the TeX version of scientific notation would not match as a number, and would give an error.

To test the patch, use

Context("Matrix")->texStrings;
$P = Point(1,2,3);
$V = Vector(1,2,3);
$M = Matrix([1,2],[3,4]);
$a = Real(1230000);
$b = Real(123000);

sub TEST {
  my $test = shift;
  my ($result, $error) = PG_restricted_eval($test);
  TEXT($error? "$test: $error" : "$test: OK", $BR);
}

TEST('$a*$P');
TEST('$P/$a');
TEST('$a*$V');
TEST('$V/$a');
TEST('$a*$M');
TEST('$M/$a');

TEXT($HR);

TEST('$b*$P');
TEST('$P/$b');
TEST('$b*$V');
TEST('$V/$b');
TEST('$b*$M');
TEST('$M/$b');

Without the patch, all the lines involving $a should produce an error, but the ones with $b should be marked OK. With the patch, all the lines should be OK.

[mgage]

Works fine. Thanks very much Davide. That removes an annoyance I've been working around.