Fix transport cargo visibility in GDI01 and GDI02.
Allow integers to bridge to enums.
Fix landing craft reinforcements in GDI01 and GDI02.
Polish GDI01:

* Insert initial forces via landing craft.
* Remove unbuildable concrete wall from production palette.
* Fix chat sounds and reinforcement notification overlapping FMV.
* Cut down the excessive starting forces to encourage base building.
* Require Silo capture/destruction for victory.
Require silos to be captured or destroyed in GDI02.
Merge pull request #6836 from pchote/polish-gdi0102

Closes #6757
Closes #6834