Added an errorformat for eslint's warning messages
fixup
README: minor update.

The official way to install pathogen has changes slightly.
Add a link to the syntax checker guide.
Merge pull request #1062 from benekastah/master

Added an errorformat for eslint's warning messages
GitHub has changed the addresses for user content.
Manual: add a note about PowerShell.
Merge branch 'master' into develop