Fix line that was too long
Add summary of virtual environment commands for anaconda and virtualenvwrapper
Condense git installation/configuration instructions
Fix typographic errors
Minor wording changes and link updates
Add link to git basics
Update thumbnail of fork button on github
Replace git/GitHub installation and configuration with link to separate document
Separate guidelines from workflow
Update thumbnails of github interface
Add labels for cross-referencing
Move virtualenv information to a separate document
Move new contributing docs into workflow folder
Extensive rewrite of workflow for developers, with some details moved to separate files

The rewrite focus moron the needs of new contributors, less on the needs of experienced developers.
Note that virtualenvwrapper does not work in all shells

…and a few formatting changes
Add recommendation to use virtual environments
Simplify list of ways to contribute
Make developer documentation a top-level heading separate from contributing