Revert "Revert "Turn DropClientMsg into a SyncMessage because it will call back into the VM""

This reverts commit 31b057479b015322605161b6f41cfaf5371a7c37.
Revert "Stop using entityState_t.solid for transmitting bboxes over the"

This reverts commit 615c3c3c6e7aa6d6c71085015a48675b7e21ff4c.
Revert "Fix 615c3c3."

This reverts commit 1e1171bf0377e1a8522056d982824be6cb6dd410.
Merge branch 'for-0.34'