Add more indentation rules and highlighting.

I made several commits for clearness, or should I squash them into a single one?

SRFI-64 (tests) is rather big, so I could miss some things that should be indented specially. Also I added highlighting for procedures that can be used in the top-level (test-begin, test-eq, ...), but maybe it's too much, and only test-group-with-cleanup and test-with-runner should be highlighted, WDYT?