Almar

- The destination concept tags now default to the source concept tag. So `lokar rename '651 Test' 'Test'` gives the same result as `lokar rename '651 Test' '651 Test'`

- Breaking change: New and more flexible command line syntax, see README for details
- Add support for "splitting subjects" (replacing a subject A with two subjects B and C)
- Bail out early if we pass the SRU limit of Alma rather than waiting for 10,000 records to be retrieved, 6
- Add `--version` flag
- Packaging: Require `lxml` rather than just using it if available (maintaining support for two different xml libraries became too much hassle)