WT: animations & frames contextual menus

[Joey79100]

WadTool's animation editor has an Animations menu and a Frames menu in its menu bar:

The timeline has a contextual menu:

The animations list has no contextual menu (right clicking on the list just does nothing).

---

For convenience, there should be contextual menus for both cases, with at least the following entries (without removing the existing ones in the case of the timeline menu):

• Animations menu:
  • Cut
  • Copy
  • Paste
  • Import...
  • Export...
  • Delete animation
• Frames menu:
  • Insert frame after current one
  • Insert (n) frames after current one
  • Delete frames
  • Cut
  • Copy
  • Paste
  • Interpolate frames