spool.select doesn't support relative argument

[d-chambers]

Description

Patch.select supports a relative argument. Spool.select does not, but it should.

Example

spool = spool.select(time=(1, -1), relative=True) 

should trim 1 second from start/end of spool. Currently it just fails silently since extra kwargs are being suppressed.

[d-chambers]

Fixed by #751 (spool index backend). Spool.select now accepts relative and no longer swallows it as an unrecognized kwarg.

Verified on dev:

spool = dc.get_example_spool()
spool[0].shape                                    # (300, 2000)
spool.select(time=(1, -1), relative=True)[0].shape  # (300, 1750)