mce_external_plugins filter can return incorrect value

[timelsass]

The mce_external_plugins filter returns an incorrect value when not on a post that is a post type post or page in the class Boldgrid_Framework_Editor. This can cause conflicts with other plugins that may not be checking type on the filtered value before trying to access it.

[timelsass]

see patch provided for the "E-Signature" plugin as reference: https://gist.github.com/timelsass/8ad0e7b3b7444b149097ac1ace250a30