Clearly separate code, data, and doc files

[larskuhtz]

Currently it is hard to distribute test binaries without including all code because data files and code files are stored side by side in the same directories and somewhat inconsistently.

Different file types should be stored in well-defined locations. In particular code files (*.hs, and *.c, *.h) should not be mixed with test data (*.pact, *.yaml, *.repl, etc.). Also data files should be registered in pact.cabal appropriately.

[larskuhtz]

Here is a list of data files and locations that are used by the tests:

./docs/
./golden/
./examples/
./tests/*.json
./tests/*.yaml
./tests/Utils/eth-keys.txt
./tests/add-sig/
./tests/cont-scripts/
./tests/lcov/
./tests/pact/
./tests/sign-scripts/
./tests/bench/bench.pact
./tests/bench/bench.repl

[jwiegley]

This makes sense to me.