Allow overbuilding on a sector

[v79]

When placing a building on a hex segment, you should be able to overbuild most buildings. Doing so will delete the original building, and increase the total build time and influence cost of the new building.

• When placing a building, add a visual indicator if it will overbuild an existing building
• For each segment of the original building, increase the total build time and the total influence cost by 1
• Show message indicating this
• When confirming the build action, add an additional confirmation step if it is overbuilding (maybe}
• Once confirmed, ensure that the ongoing build action has the correct run time
• Ensure that the building to be deleted is deleted on the first turn and no longer provides its benefits

Other notes:

• Can only overbuild a completed building, not a construction site