Fix gcc 8.1 build

See merge request !16

removed pointer Job* from cUnit, as this introduced circular references between game objects, which cannot be deserialized. The pointer wasn't needed anyways...

improved surveyor ai: it now plans the whole move for the turn at once. Also plans more efficient routes, so it will survey more field per turn.

Fix building with MSVC

See merge request !14

The C++ standard forbids constant value types as arguments to containers and the most recent MSVC compiler enforces this rule.