`subtree`command doc
extended the documentation for subtree
Allow the work-item association regex to be overridden by user config.

This is intended to resolve issue #512 by allowing the user git config to
redefine the regular expression used to match work-item id's in the commit
message. This is useful in those cases where a project may be using an
alternative system to track bug id's.

The user may define the git config variable git-tfs.work-item-regex to
use an alternate regular expression. If this is undefined or en empty
string then the built-in default is used (matching # followed by digits).
If the expression fails to compile then no matching will be attempted.

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
Document the work-item association match override config variable.

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
Don't fetch files that we're going to ignore.
Add to changelog.
Add a test for ignore-regex.
:cool: with commits that have only ignored content.
Add a test that shows a problem with fetching + ignore + rename.
Also rename a file from not ignored to not ignored.
Extract ChangeSieve from TfsChangeset.
Fix a couple of markdown links in documentation

Backticks surrounding the entire text of a link cause it to be rendered `[like this](http://)` instead of [`like this`](http://).
Merge pull request #523 from brantb/patch-1

Fix a couple of markdown links in documentation
Merge pull request #513 from patthoyts/pt/work-item-match

Allow work-item association matching to be overridden by user config variable.

Closes #512
Start testing ChangeSieve.
formatting...
Merge pull request #487 from pmiossec/subtree_doc

`subtree`command doc
Test change sorting.
Update README.md for subtree command
Capture the current handling of renames and ignore rules.