Provide read_graphml

[jiahao]

Reads in GraphML files and returns a LightGraph object.

Requires LightXML as an optional dependency

[coveralls]

Coverage decreased (-2.96%) to 91.97% when pulling f1ceffe on jiahao:cjh/read_graphml into 19be9c7 on JuliaGraphs:master.

[jiahao]

What's this package's policy on @doc strings? I see some functions have them commented out. Can we introduce a dependency on Docile.jl to handle 0.3 compatibility?

[coveralls]

Coverage decreased (-2.96%) to 91.97% when pulling f1ceffe on jiahao:cjh/read_graphml into 19be9c7 on JuliaGraphs:master.

[sbromberger]

What's this package's policy on @doc strings? I see some functions have them commented out. Can we introduce a dependency on Docile.jl to handle 0.3 compatibility?

@jpfairbanks uses them; I don't :) They were commented out because they broke 0.3 without Docile. Given that docstring format is still up in the air for 0.4 I'm inclined to not have them right now.

[jiahao]

Ok, I commented them out.

[sbromberger]

This is awesome, btw. Thank you. I'll add some docs later.