Gravity Perks - Nested Forms 1.1.69

Fixed potential PHP error upon submission of a child form if a submitted input references a field that does not exist.
Fixed an issue where calculations using GPNF merge tags such as {Field:1:total} could sometimes trigger a JavaScript error.

Updated the class name to disable responsive table styling. It is now gpnf-disable-responsive-table rather than gpnf-disable-table as the latter did not make sense.

Added ability to disable responsive table styling by adding gpnf-disable-table as a class to parent forms.
Fixed potential PHP warning.