vchoi_fork

Elaborate on the H5ES routines, starting to add API routines.

Update the "close ID" callbacks to allow asynchronous request tokens to be
passed in from an asynchronous close API call.

Refactor current asynchronous API routines (H5Fopen/H5Fclose and
H5Dread/H5Dread) to use event sets instead of directly working with request
tokens from the application.

Clean up a few other minor warnings & code style issues.