support import / export of text and animations

[matthiasbalke]

Scenario:

• I transfer my texts and animations to the blinkenrocket from my desktop pc.
• some days later I want to show blinkenrocket to a fried of mine, I only have my notebook available so I have to override all texts and animations I did.

As I animated an tetris scene in the first place which took quite some time, I do not whant to loose this animation.

Solution:

• Add export / import functionality so users can save their texts and animations locally or in the cloud (e.g. dropbox, google drive, etc.)
• afterwards one can load a previously saved text or animation and transfer it again without having to recreate it.
• (optional) import / export specific texts or animations, so users can share single texts / animations with each other and compose their specific collection from it.

[barnslig]

See pull request #3 for a basic implementation!