Testing indexing FASTQ file with zero length record (issue #269)

Example file from Sam Hunter, included in his bug report.

Tests/Quality/zero_length.fastq

@@ -0,0 +1,20 @@
+@EMWLCP001DET6P
+CCCATCATTTATAATTTTAACACGTCCTAGCGTGTAATCTACGGTAT
++
+NA+<?;8M@*?=C4UE6'J<:=>??K=????;>?>K==????K>?>;
+@EMWLCP001CB6TP
+CAGAGTTGCAAGTGCCGGTAATCGCCCTCTCACAGCTGAACCGTGGGCCAGAGCAGCGAGCCGACAAGATGCCGGCCCTGAGCGACCTGCGTGAGTCGGGTTCGCTCGAGCAAGACGCCGACCTAGT
++
+?;??>K>?>K>=??K>K>?K>?><RD1??????><?>>K>K>>?RD1K>??>>??????>J=??<K>?><=K>J=PC.??>?>?=I<?>=>>?;=<?PC.J=>:=?;>?>?K=>4<<K=>>F8>>?=
+@EMWLCP001DHOHL
+
++
+
+@EMWLCP001C1YIG
+CAGAGGCAAAATGAGAAGGCAGAAAGGGATAGGAGCTG
++
+>??;I;?TD4%>>>?E7G9=>?PC.PC.<??K>>?>?K
+@EMWLCP001AOVPY
+CAGTCGGACAGGCGCAGTTCATGGCGGCGCGAGCACACCGTTTCGCCCAGGTAGACGATGTCCACAGG
++
+>>><?K>???K>??>??K><=?K>?K>????=<???<K=>RD1><RD1?K>>?=>?=????K>?>>K=

Tests/test_SeqIO_index.py

@@ -380,6 +380,7 @@ tests = [
     ("Quality/sanger_faked.fastq", "fastq-sanger", generic_dna),
     ("Quality/solexa_faked.fastq", "fastq-solexa", generic_dna),
     ("Quality/illumina_faked.fastq", "fastq-illumina", generic_dna),
+    ("Quality/zero_length.fastq", "fastq", generic_dna),
     ("EMBL/epo_prt_selection.embl", "embl", None),
     ("EMBL/U87107.embl", "embl", None),
     ("EMBL/TRBG361.embl", "embl", None),