Caption support (#2462)

Co-authored-by: WithoutPants <53250216+WithoutPants@users.noreply.github.com>

vendor/github.com/asticode/go-astikit/defer.go

@@ -0,0 +1,57 @@
+package astikit
+
+import (
+	"sync"
+)
+
+// CloseFunc is a method that closes something
+type CloseFunc func() error
+
+// Closer is an object that can close several things
+type Closer struct {
+	fs []CloseFunc
+	m  *sync.Mutex
+}
+
+// NewCloser creates a new closer
+func NewCloser() *Closer {
+	return &Closer{
+		m: &sync.Mutex{},
+	}
+}
+
+// Close implements the io.Closer interface
+func (c *Closer) Close() error {
+	// Lock
+	c.m.Lock()
+	defer c.m.Unlock()
+
+	// Loop through closers
+	err := NewErrors()
+	for _, f := range c.fs {
+		err.Add(f())
+	}
+
+	// Reset closers
+	c.fs = []CloseFunc{}
+
+	// Return
+	if err.IsNil() {
+		return nil
+	}
+	return err
+}
+
+// Add adds a close func at the beginning of the list
+func (c *Closer) Add(f CloseFunc) {
+	c.m.Lock()
+	defer c.m.Unlock()
+	c.fs = append([]CloseFunc{f}, c.fs...)
+}
+
+// NewChild creates a new child closer
+func (c *Closer) NewChild() (child *Closer) {
+	child = NewCloser()
+	c.Add(child.Close)
+	return
+}