Implement rsync like include and exclude - fixes #27

* 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

docs/content/docs.md

@@ -288,3 +288,22 @@ here which are used for testing.  These start with remote name eg
 ### --cpuprofile=FILE ###
 
 Write cpu profile to file.  This can be analysed with `go tool pprof`.
+
+Filtering
+---------
+
+For the filtering options
+
+  * `--delete-excluded`
+  * `--filter`
+  * `--filter-from`
+  * `--exclude`
+  * `--exclude-from`
+  * `--include`
+  * `--include-from`
+  * `--files-from`
+  * `--min-size`
+  * `--max-size`
+  * `--dump-filters`
+
+See the [filtering section](/filtering/).