Initial creation of CRAM validation / test files

The files are numbered such that a natural sort order will mean the
earlier files may be decodable without yet being able to decode any of
the later files.  Therefore this may optionally be considered as a
roadmap for development of new CRAM decoders.

Indices are also tested.

test/cram/ce.fa.fai

@@ -0,0 +1,7 @@
+CHROMOSOME_I	1009800	14	50	51
+CHROMOSOME_II	5000	1030025	50	51
+CHROMOSOME_III	5000	1035141	50	51
+CHROMOSOME_IV	5000	1040256	50	51
+CHROMOSOME_V	5000	1045370	50	51
+CHROMOSOME_X	5000	1050484	50	51
+CHROMOSOME_MtDNA	5000	1055602	50	51