Rustfmt is still so immature that developers can't have different versions
installed, or there will be minute differences in formatting causing the tests
to fail.
Only run rustfmt as part of the test-all script if the expected version is
available.
The integration tests use both libcretonne and libreader, so moving them avoids
the circular dev-dependency.
Also go back to building everything under src/tools/target to avoid rebuilding
the libraries when cargo is invoked in different subdirectories. This speeds up
test-all.sh quite a bit.
Finally, skip the pure debug build. We build "cargo test" and "cargo build
--release" which should cover everything we need.
Move test-all.sh to the top level directory, and also run the parser tests from
this script.
Use a release build of cton-util to run the parser tests. As we accumulate many
tests in the tests directory tree, this will mean they can still be run quickly.
Point Travis config to the new test script.
