add test for having a multiple arg with an int conversion
Expand test cases for type conversion with multiple=True
get_value returns Missing even if multiple=True
Merge branch 'multiple-missing' into dev
Fix repr of Missing
Filter out extra arguments

fix #28
Update docs

Update changelog
Use sphinx-issues
Add project links to README/long-description
Merge branch 'docs' into dev
Fix typo in docs
Raise RequiredArgMissingError when a required argument is missing
Merge branch 'required-error' into dev
Add RequiredArgMissingError to __init__

also update tagline
Fix typos
Bump version and update changelog