Merge pull request #200 in HDF5VOL/daos-vol from ~NFORTNE2/daos-vol:master to master
* commit 'c38866b50a916c08d6246918f3a702b438209876':
Minor fixes.
Add failed operation reporting to error handling code (in addition to failed low level task). Add support for operation canceling (not tested). Change internal object opens/creates to use temporary internal requests instead of sharing the request of the top level operation, to prevent hangs. Various other minor changes.
More fixes to async code.
Propagate async code to the remainder of interfaces so interactions between sync and async code don't cause issues (there are still routines that block). Other fixes. Update API specific support in users's guide.
Add links in user's guide to HDF5 async documentation.
