200 line limit in read_bibliography()

[wilkox]

I was getting an error when running read_bibliography() on a RIS file downloaded from EMBASE:

Error in detect_delimiter(zsub) : 
  import failed: unknown reference delimiter 

It turned out that only the first 200 lines of the reference were being read, which caused detect_delimiter() to subsequently fail to detect that the reference ended with an ER line and was therefore "endrow" delimited. Replacing lines 93-94 of read_bibliography.R with:

zsub <- z[seq_len(length(z))]

fixed the problem.

Is there a reason for the 200-line limit? Otherwise would you accept a pull request with the change I made?