Fix raw pointer conversions with respect to arithmetic.
Fix dependencies for 'make test'.
Test calling variadic functions via stub generation.
Test passing complex numbers by value using stub generation.
Test passing unions by value using stub generation.
Test passing structs with union members using stub generation.
Test passing structs with array members using stub generation.
Add missing header.
Merge pull request #144 from yallop/stub-specific-tests

Stub-generation-specific tests
Set DYLD_LIBRARY_PATH when running tests on OS X.
Use 'close' rather than 'fdopendir' in the errno test.

'fdopendir' is not available on OS X.
Merge pull request #145 from yallop/macos-test-fixes

Macos test fixes
Introduce a 'bind' function for constructing C ASTs.
Normalize the AST during construction.
Capture some invariants in the C AST type.

The RHS of a let binding cannot be another let binding.
Return is now only allowed in the final position.
Only globally-bound functions can be called.
Distinguish global functions from variables in the C AST types.
Pull out local variables as a separate type.
Name the type of C bindings (x = e).
Merge pull request #146 from yallop/generate-normal-form

Represent generated C code in normal form
Introduce `string ocaml' and `float array ocaml` direct-mapping types.