Hi, and thanks for the code updates, the ARC writer is
starting to look good.  Here's todays fun questions:

Is there a way to adjust when the contents are stored in a
file rather than in memory?  Otherwise, I'll have to figure
out chunkwise MD5sum and all that -- if the htsblk->out is
opened for reading at all, otherwise how do I get at the file?
Can I get my hands on command-line arguments from a plugin?I'd like to add
some parameters specific to the plugin.

Can I either turn off the use of HEAD requests, or at least
find out in the htsblk whether this is a HEAD request?  I
don't want to store the HEAD result when it's followed by a
GET anyway.

-Lars