Handle exceptions in int conversions (#2092)

* RageUtil: Add exception-safe wrappers around std::stoi, stol, stoll

* Replace use of std::stoi with exception-safe StringToInt

src/NotesLoaderBMS.cpp

@@ -483,7 +483,7 @@ struct bmsCommandTree
 			while (randomStack.size() < currentNode->branchHeight + 1) // if we're on branch level N we need N+1 values.
 				randomStack.push_back(0);
 
-			randomStack[currentNode->branchHeight] = rand() % std::stoi(value) + 1;
+			randomStack[currentNode->branchHeight] = rand() % StringToInt(value) + 1;
 		}
 		else
 		{
@@ -886,12 +886,12 @@ void BMSChartReader::ReadHeaders()
 		}
 		else if( it->first == "#playlevel" )
 		{
-			out->SetMeter( std::stoi(it->second) );
+			out->SetMeter( StringToInt(it->second) );
 		}
 		else if( it->first == "#difficulty")
 		{
 			// only set the difficulty if the #difficulty tag is between 1 and 6 (beginner~edit)
-			int diff = std::stoi(it->second)-1; // BMS uses 1 to 6, SM uses 0 to 5
+			int diff = StringToInt(it->second)-1; // BMS uses 1 to 6, SM uses 0 to 5
 			if(diff>=0 && diff<NUM_Difficulty) {
 				out->SetDifficulty( (Difficulty)diff );
 			}