[interchange] * Add "default" option on CGI tag. Negligible impact on performance, as

commit 12d531675b82a0654117f362d4939c697e66906d
Author: Mike Heins <[email protected]>
Date:   Wed Jul 6 21:56:48 2016 -0400

    * Add "default" option on CGI tag. Negligible impact on performance, as
      branch only followed on blank/zero value.
    
    * Close Issue #94 on Github.

 code/SystemTag/cgi.coretag |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/code/SystemTag/cgi.coretag b/code/SystemTag/cgi.coretag
index 39b146a..e35a90b 100644
--- a/code/SystemTag/cgi.coretag
+++ b/code/SystemTag/cgi.coretag
@@ -24,6 +24,10 @@ sub {
 		$value =~ s~<([A-Za-z]*[^>]*\s+[Mm][Vv]\s*=\s*)~&lt;$1~g;
 		$value =~ s/\[/&#91;/g;
 	}
+	elsif(defined $opt->{default}) {
+		$value = $opt->{default};
+	}
+
 	if($opt->{filter}) {
 		$value = filter_value($opt->{filter}, $value, $var);
 		$CGI::values{$var} = $value unless $opt->{keep};