[WW integration] view and add github issues from Lively

[lauritzthamsen]

Use the Markdown morph to interface github issues in Lively. Load title, label, and issue description from github, while Lively worlds provide an environment for the reproduction of defects or general examples.

[lauritzthamsen]

From discussion in issue 4:

github API, e.g. issues and repos.
a little entry in the world menu that says "report a bug" that will then automatically create a github issue
also when a red error message pops up. alerts [...] could automatically be used for the description...!

[rksm]

...and later also make the github wiki browsable and editable in Lively. I feel that the more restricted form of this kind of documentation will make it simpler to organize and style it. The "free form" documentation we have now simply isn't really accessible, e.g. for processing and embedding t somewhere else.

[rksm]

Issues are now being displayed in proper github markdown mode via apis.Github.Issues.ui