Use integrated graphics on laptops

Before using the 'Open…' dialog caused the discreet graphics chip to be enabled until TextMate exited. Setting this flag tells the OS that we want and are able to use the integrated graphics to conserve the battery. Detailed in Apple Technical Q&A QA1734:

http://developer.apple.com/library/mac/#qa/qa1734/
Support relative includes in tests

Since we inline the test file, rather than include it, relative includes from this inlined code would not work.
Make semi-internal API private

This was previously public so that we could write tests for it, but since the test runner is linked with the object files, it can access symbols that has visibility set to hidden.
Remove unused private field

Basically to avoid a clang warning.
Don’t call super in main menu key equivalent handler

It was calling super to keep our custom code to a minimum, but it turns out that the superclass will sometimes invoke bundle menu items even when items from the other menus are better candidates.

Partially reverts 4b0a9a08c7cea550cf83e48d2471770e6b1fefb2.