patch 8.0.0499: taglist() does not prioritize tags for a buffer

Problem:    taglist() does not prioritize tags for a buffer.
Solution:   Add an optional buffer argument. (Duncan McDougall, closes #1194)
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 5fa31a2..ff1b71f 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -2363,7 +2363,7 @@
 tabpagebuflist([{arg}])		List	list of buffer numbers in tab page
 tabpagenr([{arg}])		Number	number of current or last tab page
 tabpagewinnr({tabarg}[, {arg}]) Number	number of current window in tab page
-taglist({expr})			List	list of tags matching {expr}
+taglist({expr}[, {filename}])	List	list of tags matching {expr}
 tagfiles()			List	tags files used
 tan({expr})			Float	tangent of {expr}
 tanh({expr})			Float	hyperbolic tangent of {expr}
@@ -7741,8 +7741,13 @@
 		for the current buffer.  This is the 'tags' option expanded.
 
 
-taglist({expr})							*taglist()*
+taglist({expr}[, {filename}])				*taglist()*
 		Returns a list of tags matching the regular expression {expr}.
+
+		If {filename} is passed it is used to prioritize the results
+		in the same way that |:tselect| does. See |tag-priority|.
+		{filename} should be the full path of the file.
+
 		Each list item is a dictionary with at least the following
 		entries:
 			name		Name of the tag.