Check that IdP names contain content before attempting translation.

getTranslation() will throw an unhandled exception when passed an
empty array, and there's no use in checking for translations of
empty stuff anyway.
Add the tracking identifier to the error message, so that we can track the logs and see what happened when someone gets this error.
Fix a bunch of documentation typos

Fix a bunch of typos in the documentation of the consent module
Merge pull request #102 from gollmann/fix-typos

Fixed a bunch of documentation typos
Merge pull request #97 from thijskh/master

Check that IdP names contain content before attempting translation.
Merge branch 'feature/short-sso-trackid'

* feature/short-sso-trackid:
  Add the tracking identifier to the error message, so that we can track the logs and see what happened when someone gets this error.
Import the "required" flag of attributes

Pass the “required” status of requested attributes from XML metadata to
metadata-generated/saml20-sp-remote.php. Required attributes are added
to an “attributes.required” element.
Merge branch 'required-attributes' of https://github.com/gollmann/simplesamlphp into required-attributes