Strip BOM before processing records

[holub008]

Resolves #13

Functional Changes

This change strips a BOM character, if present, from both the load (file based) and loads (string based) entry points to the RIS parser.

Testing

I added a new test case. I verified the test file includes a BOM character via:

hexdump -n 15 -C tests/data/example_bom.ris 
    00000000  ef bb bf 54 59 20 20 2d  20 4a 4f 55 52 0a 44     |...TY  - JOUR.D|
    0000000f

Ran tests via make test (12/12 passed, whereas 11/12 passed before changes) and checked formatting via make lint.

[shapiromatron]

thanks @holub008! I'll wait on minting a new version unless you need it

[holub008]

@shapiromatron Not a problem to wait - it's easy enough to implement the change in a forwards compatible way outside loads.