Fix typo in paymill.php
Merge pull request #2 from felixfischer/master

Fix typo in paymill.php
readme: installation: hint at paybutton and shortcode
fix typo in form class name
Merge pull request #4 from mk-pmb/typommill

fix typo in form class name: paym[m]ill_subscription
Merge pull request #3 from mk-pmb/readme_shortcode_hint

readme: installation: hint at paybutton and shortcode
1.6

#2