Explains that filtering is done relative to the remote root.
Also removes a section that seems more about internal knowledge and
that may likely more confuse people. Adds instead a section giving an
overview of how to perform filtering before going into details.
This means you can mix `--include` and `--include-from` with the
other filters (eg `--exclude`) but you must include all the files you
want in the include statement.
Fixes#280
* Implement include/exclude
* Implement rsync compatible file globbing
* Implement command line filtering flags
* --delete-excluded - Delete files on dest excluded from sync
* --filter - Add a file-filtering rule
* --filter-from - Read filtering patterns from a file
* --exclude - Exclude files matching pattern
* --exclude-from - Read exclude patterns from file
* --include - Include files matching pattern
* --include-from - Read include patterns from file
* --files-from - Read list of source-file nam
* --min-size - Don't transfer any file smaller than this in k or suffix k|M|G
* --max-size - Don't transfer any file larger than this in k or suffix k|M|G
* Document
