Removed unnecessary variable definition
Moved hideCheck out of if clause

Otherwise the property would not be set for example on fields
with input_field_callback
Do not use class invisible on table element

Otherwise the table header columns would collapse, meaning the header
for column 3 will appear at position 2, if position 2 is invisible.
Fix menatwork/MultiColumnWizard#159 Incompatibility with other widgets
Merge pull request #164 from madeyourday/fix/file-picker-incompatibility

Fix incompatibility with other widgets
Merge pull request #161 from aschempp/dev

Fixed hideHead