Same principle as removing the separate variable to track number of
collected trinkets. This means it's less error-prone as we're no longer
tracking number of trinkets separately.
In the function that counts the number of trinkets, I would've liked to
have used std::count_if(). However, the most optimal way would require
using a lambda, and lambdas are too new for the C++ standard we're
using. So I just bit the bullet and counted them manually.
game.trinkets is supposed to be correlated with obj.collect, however why
not just count obj.collect directly?
This turns game.trinkets into a function, game.trinkets(), which will
directly count the number of collected trinkets and return it. This will
fix a few corner cases where the number of trinkets can desync with the
actual collection statuses of trinkets.
In order to keep save compatibility with previous versions of VVVVVV,
the game will still write the <trinkets> variable. However, it will not
read the <trinkets> variable from a save file.
