Add PrepareSerializer<T>() method to the TLRig.
Change behavior of getting serializer from TLRig.

Now result can be null instead of throwing an exception.
Improve performance of TLVectorSerializer.
Improve TLRigFacts.
Remove PerformanceTests.

Moved to https://github.com/inTagger/SerializersRace.
Change version to 0.7.2.
Merge branch 'develop'