Support extra information, such as git describe, in version string
Add stubs to make physics code more like D2X
Simplify logic for robot to drop proximity bomb
Use ubyte/const ubyte consistently in multiplayer messaging
Add helper to get pointer to reactor definition
Fix debug=1 build break from fe7cf3bc ("Move segment handling from editor.h")

When debug is enabled, gamecntl references symbols that moved to the new
header.
Add proximity bomb ID test helper to match D2X
Add multi_send_robot_explode unused parameter isthief to match D2X