Added FocusItem and FocusItemList.
DropIntoArray action and test.
Added FrameWidget.
Added FramesTimeline.
Added FramesTimelineTest.
Added description to Frame#time .
Added StretchableButton, you can change it size by dragging.
Comments addressed.
Adjusted EditorGameAssets#resolve and test fix.
Merge pull request #667 from gorco/StrButton

Added StretchableButton.
Merge pull request #663 from RotaruDan/FramesTimeline

Frames timeline
    Added ConversationSystem, DialogueSystem

    - ConversationSystem processes a TalkComponent, which is added by
      TriggerConversation effects. They are display-independent.

    - DialogueComponent processes DialogComponents, which can specify
      callbacks. Currently they all have the same style; this will
      be addressed in later commits.
Added ConversationDemo

Click on dialogues to choose / dismiss them.
Add a components.dialogue package, systems.dialogues package

Since there are now two types of dialogues (menu and line)
Cleaner, call-back free conversations.

Conversation advancement is done via polling. Removed logging.