Add Cargo.png to all repositories with dependencies

[bvssvni]

See #643 for how to generate dot files.

• Generate "Cargo.dot" for all repositories with dependencies
• Generate "Cargo.png" from all dot files
• Add ![dependencies](./Cargo.png) to all READMEs with title "Dependencies"

[bvssvni]

• hematite
• sprite
• event
• ai_behavior
• rust-graphics-lab
• graphics
• gfx_voxel
• cam
• conrod
• asset_store
• sdl2_window
• opengl_graphics
• gfx_graphics
• rust-dsp
• glfw_window
• texture-packer

[TyOverby]

This could be done automatically by our Travis-Ci builds.

[indiv0]

@TyOverby where would it be put?

[TyOverby]

I was thinking that Travis-Ci could automatically generate the dot-files, and then upload them to some server like we do with rust-ci.

It would require that server, but we'd never need to worry about updating them ever again.

[indiv0]

@TyOverby yeah the server aspect was what I was asking about.

The most reasonable approach to me seems like submitting a PR to rust-ci to add this functionality.
This way, the infrastructure it already in-place and the only thing needing to be changed is the rust-ci project itself.

[bvssvni]

The only remaining is asset_store, due to some confusion around the README file.

Closing.