escape underscores in function signatures

Underscores can be interpreted as hyperlinks so they must be escaped in code.
Also fix spliting of the function name and formal parameters when the parameters
contain default values with parens in them.

docs/gen_reference_doc.py

@@ -149,7 +149,7 @@ def is_visible(desc):
 	return True
 
 def highlight_signature(s):
-	name = s.split('(')
+	name = s.split('(', 1)
 	name2 = name[0].split(' ')
 	if len(name2[-1]) == 0: return s
 
@@ -168,6 +168,9 @@ def highlight_signature(s):
 	# we also have to escape colons
 	name[1] = name[1].replace(':', '\\:')
 
+	# escape trailing underscores
+	name[1] = name[1].replace('_', '\\_')
+
 	# comments in signatures are italic
 	name[1] = name[1].replace('/\\*', '*/\\*')
 	name[1] = name[1].replace('\\*/', '\\*/*')