Changes for mod implementation

[hogsy]

• [x] Rename 'campaigns' directory to 'mods'
• [x] Change mod manifest extension to '.mod' rather than '.campaign'

Properties

Variable	Description
name	The name of the modification.
author	Creator/s of the modification.
version	Version of the modification.
dependencies	Array of modifications this mod depends on.
dependencies > name	The name of the mod we depend on.
dependencies > version	The version of the mod we depend on.

Scenarios structure will stay the same for now. Might be worth considering moving it into it's own scripts/scenarios dir though? 🤔

[hogsy]

Done in mod-mounting branch, closing.