vcf: Abort on broken VCFs with multiple/trailing spaces/tabs
vcf: Don't let unpack_*_core forget the to-be-freed pointer
hts_expand0: type ptr properly, it can be of different type
Merge pull request #60, CRAM EOF block improvements
Reduced the number of realloc calls zlib_mem_inflate(), while
hopefully not overallocating much either.

Forcibly set block->alloc field when decompressing from gzip or
bzip2. This caused issues in scramble, but doesn't seem to in samtools
due to no ability to set compression level higher. Fixing it here just
incase though.