Tweak mod that integrates cargo ships into arig gameplay

List of changes:

• A new infinite resource called offshore-heavy-oil, which generates only on sea of sands.
• Heavy oil must be extracted using offshore rigs, making maritime transport necessary.
• Advanced heavy-oil processing technology now unlocks through interacting with the Arig crash site.
• The Arig crash site yields additional heavy-oil barrels.
• A missing prerequisite is added to keep Arig’s technology progression consistent. Arig planet discorvery now require oil rig to be researched first