Add context.HandlerNames() (#1729)

* Add context.HandlerNames()

This change adds a HandlerNames method that will return all registered handles in the context, in descending order

This is useful for debugging and troubleshooting purposes, especially in large apps

* Tests

Add tests for HandlerNames

* Fix HandlerNames test

* Simplify test

context_test.go

@@ -340,10 +340,26 @@ func TestContextHandlerName(t *testing.T) {
 	assert.Regexp(t, "^(.*/vendor/)?github.com/gin-gonic/gin.handlerNameTest$", c.HandlerName())
 }
 
+func TestContextHandlerNames(t *testing.T) {
+	c, _ := CreateTestContext(httptest.NewRecorder())
+	c.handlers = HandlersChain{func(c *Context) {}, handlerNameTest, func(c *Context) {}, handlerNameTest2}
+
+	names := c.HandlerNames()
+
+	assert.True(t, len(names) == 4)
+	for _, name := range names {
+		assert.Regexp(t, `^(.*/vendor/)?(github\.com/gin-gonic/gin\.){1}(TestContextHandlerNames\.func.*){0,1}(handlerNameTest.*){0,1}`, name)
+	}
+}
+
 func handlerNameTest(c *Context) {
 
 }
 
+func handlerNameTest2(c *Context) {
+
+}
+
 var handlerTest HandlerFunc = func(c *Context) {
 
 }