Creating Mission Planner Plugin

#### Issue details
I'm creating a new Mission Planner plugin and I'm trying to generate a new aspect for the grid plugin. I'm copying all the contents of the Grid folder and putting them into my plugin project. I'm only able to run it if the PluginHost of the Plugin Class has the set modifier to public (not internal), could it be changed? Thanks.

#### Version
_1.3.56_

The issue names the Grid folder, PluginHost, and Plugin Class but no repository file or test. Locate those references first, reproduce the external-plugin setup described for version 1.3.56, and confirm that the plugin runs without requiring a public modifier.

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