Clean up unused modules

[tomsmeding]

Description
There are some unused modules in the src/ tree. To better support grepping the source tree, let's move them away.

There is one additional module that is not enabled in the cabal file but does exist in the src/ tree (Data.Array.Accelerate.Test.NoFib.Issues.Issue286), but since this is a test that requires manually looking at heap profiles to see if the test "passed" (and is hence presumably disabled because it's rather pointless to run that as part of the automated test suite), I left this module in place.

Motivation and context
Making grepping the source tree easier, and preventing confusion like "what is this code doing? Wait it's not even used?"

How has this been tested?
Tests pass, but "cabal is happy" is rather more relevant here.

Types of changes
What types of changes does your code introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist
Go over all the following points, and put an x in all the boxes that apply. If you're unsure about any of these, don't hesitate to ask. We're here to help!

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed