Add build and test instructions
Add support for naming tasks

Mostly, so that they can't be scheduled twice
Also added support for getting status and canceling via names.
Add THANKS file
Do not clean before xref checks or dialyzing
Fix ident() definition

Mistakenly put atom() | pid() inside a tuple.
Merge pull request #2 from taybin/patch-1

Fix ident() definition
Make better use of dialyzer and xref

Create a separate oneshot/3 function to handle the non-repeating oneshot
schedule type. This fixes the dialyzer warnings that were being ignored.

Enable only the xref undefined_function_calls check rather than checking
for and ignoring exports_not_used.
Remove reference to non-existant files

Removed documentation reference to dialyzer_reference
and xref_reference files which are no longer used.
Allow task names to be binaries as well as atoms
Document cron task data types