Repeated data on some datatypes

[seanpclose]

When writing a number of samples which is a non-integer multiple of the scans per write, the following data types have extra data written to the TDMS file:

single
I64
I32
I16
I8
U64
U32
U16
U8

Suspect an issue with how the final data is written when the amoutn of data in the cache is less than the scans per write.