CheckBoxDef causes an error if you don't explicitly set a label

[valadaptive]

It appears that the API zero-initializes PF_ParamDefs, which means that a CheckBoxDef's nameptr is null by default.

After Effects doesn't like this, and will give a hard-to-debug "the plugin failed to initialize" error if you don't explicitly set the checkbox's label.

One way to fix this would be to initialize nameptr to point to an empty string, but that'd require separating out the initialization code for each type of parameter.

[AdrianEddy]

Good catch, fixed