Add 'sig_max_lines' config option to defaults (#1490071)

config/defaults.inc.php

@@ -640,6 +640,10 @@ $config['spellcheck_ignore_syms'] = false;
 // Use this char/string to separate recipients when composing a new message
 $config['recipients_separator'] = ',';
 
+// Number of lines at the end of a message considered to contain the signature.
+// Increase this value if signatures are not properly detected and colored
+$config['sig_max_lines'] = 15;
+
 // don't let users set pagesize to more than this value if set
 $config['max_pagesize'] = 200;