Menu cleanups and improvements

[tritonas00]

• Removed GUI_GamePauseMenu(cpp/h) and merged code in GUI_GameMainMenu.cpp
• Pressing Esc in multiplayer, only the menu is shown now, simulation continues
• Added "Cache updated" notice:
  

[ohlidalp]

Works great, just one detail: the "cache updated" notification only shows if cache is actually updated. If it's already up-to-date and user presses "update cache" button, nothing shows at all. I suggest adding "cache is up-to-date" variant of the notification for this case.

[tritonas00]

notification only shows if cache is actually updated. If it's already up-to-date and user presses "update cache" button, nothing shows at all

this is not the case on linux, it is always shown when i hit the update cache button
i can reproduce the issue on windows, i moved the notice to LoadModCache, also the same

[ohlidalp]

@tritonas00 I don't understand why linux behaves differently, but we definitely have a bug: CACHE_STATE_UNKNOWN and CACHE_NEEDS_UPDATE have the same value. Without this bug, the notification would always display after pressing the button.

UPDATE: I fixed the bug (and couple others I noticed), "cache updated" now displays the way you intended. Please merge these commits https://github.com/only-a-ptr/rigs-of-rods/commits/menu-cleanup and test again.

[tritonas00]

Epic