Variable $js_expiretime initialized as string rather than number

Problem/Motivation

In splashify_init(), the variable $js_expiretime is initialized as an empty string. Later, that variable is used in a context where a numeric value is expected. In practice this issue will affect only sites with a custom code interacting with Splashify since it will occur only if the variable 'splashify_when_mobile_frequency' is set to a value other than the expected ones.

Proposed resolution

Initialize the variable as a number (0) rather than an empty string.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet