Train HUD disappears after level change or save game load

[SamVanheer]

The train HUD disappears after a level change or save game load.

This happens because when either happens the game is saved and loaded. While loading CBasePlayer::Precache is called, which resets the train variable:

halflife/dlls/player.cpp

Line 2976 in c7240b9

m_iTrain = TRAIN_NEW;

This should be:

m_iTrain |= TRAIN_NEW;

The restored value is retained this way, and the flag that gets added ensures the train speed value is correctly sent to the client, which then displays the train HUD correctly.