TrecLib's TFile does not support all text encodings

[TrecApps]

While the TFile is capable of recognizing what text encoding a given file is using, it currently only has support for:

• ASCII
• Unicode-16
• Unicode-16 (little-endian)

Ideally, it should also be able to support these other encodings:

• Unicode-8
• Unicode-7
• Unicode-32 (little-endian and big)

It is recommended that those attempting to fix this issue look at the various Read/Write methods in the TFile class for inspiration on how to apply that to these other encodings.

Any Pull Requests related to this issue should request to merge in the TrecLib_improve branch.

[TrecApps]

In the environment branch, moderate support for UTF-8 is available for TFile.