Correct confusing name and fix typos

[dspinellis]

The documentation is about the testfxtures module; remove confusing references to the class-like TestFixtures name.
Also fix the completely wrong references to TestFixtures.

[cjw296]

The documentation is about the TestFixtures distribution, which I'm not sure I like capitalisation-wise anymore, but that package contains a testfixtures package.
I don't think there is a testfixtures module anymore.

I'm afraid there is nothing "completely wrong" in the text you've changed.

What problems has this text caused you that you felt the need to see if changed?

[dspinellis]

You are correct regarding the module term. I changed the module references into package references.

The references to TestFixtures made me look for a class with that name and try to use one.

The "completely wrong" parts I fixed were references to TextFixtures (Text, not Test).

[cjw296]

Ah okay, the typo fixes in their own commit would have been easier to review :-)

[dspinellis]

Thank you! BTW testfixtures is awesomely cool! It allowed me to test and debug a complex time-dependent interaction.