PR #1514 made this change to avoid having to constantly update fred.rc with new FSO versions, but it was inadvertently reverted in commit 9ac97f24223a7446d4364acfdb451c90697d6577; this also reverts PR #2286, since that's a somewhat more hackish solution to the same problem.
The amount of output parameters is becoming quite large which makes it
harder to add new input parameters. For that reason I converted the
existing output parameters to a struct which cleans up the function
signature a lot.
Now that BMPMAN dynamically allocates the bm_bitmaps array, and deallocates it in bm_close(), which is explicitly called by gr_close(), FRED generates an exception on close because of trying to release bitmap handles after bm_bitmaps has been deallocated and set to null. This is because gr_close() is called by CFREDView::OnDestroy(), but the mission textures aren't fully paged out until CMainFrame::OnClose() (well, technically, CMainFrame::OnClose() calls CFrameWnd::OnClose(), which calls CWinApp::CloseAllDocuments(), which calls CDocManager::CloseAllDocuments(), which calls CDocTemplate::CloseAllDocuments(), which calls CDocument::OnCloseDocument(), which calls CFREDDoc::DeleteContents(), which calls CFREDDoc::editor_init_mission(), which calls reset_mission(), which calls clear_mission(), which calls model_free_all(), which calls model_instance_free_all(), which calls model_unload() for every model, which calls model_page_out_textures(), which *finally* calls the crashing bm_release()). This commit moves the gr_close() call to CMainFrame::OnClose(), *after* it calls CFrameWnd::OnClose(), which avoids the exception as bm_bitmaps is still intact long enough for those final textures to be freed from it.
This introduces a new mechanism for handling bit flags. Instead of using an int (or two, or three) to write bits into, this uses the std::bitset in a wrapper class that accepts an enum class as input. This means that certain classes of errors we've had a few of in the engine, where a coder used the wrong set of flags or checked them against the wrong variable (SF_STEALTH vs SIF_STEALTH, for example) can now be detected at a compiler level rather than not at all.
Goober5000