[PATCH 1/2] Test framework take two.

[PATCH 1/2] Test framework take two.

This adds t/ directory to host test suite, a test helper
library and a basic set of tests.

Petr Baudis raised many valid points at the earlier attempts in
git mailing list.  This round, test-lib.sh has been updated to a
bit more modern style, and the default output is made easier to
read.  Also included is one sample test script that tests the
very basics.  This test has already found one leftover bug
missed when we introduced symlink support, which has been fixed
since then.  The supplied Makefile is designed to run all the
available tests.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Petr Baudis <pasky@ucw.cz>