dirstate.walk: refactor explicit walk into separate function
This enables this code to be reused by extensions that implement the other,
more time-consuming bits of walk in different ways.
dirstate.walk: pull skipstep3 out of the explicit walk code
This is a move towards factoring out this code into a separate function.
dirstate.walk: move dirignore filter out of explicit walk code
This is a move towards factoring this code out into a separate function.
dirstate.walk: maintain a list of dirs not found
Upcoming patches will factor out the walk over explicit files done in step 1.
This helps us get there.
highlight: fix page layout with empty first and last lines
Repeated newlines were stripped by pygmentize, now give the option not to do so.
tests: fix unionrepo path issue on msys (
issue3927)