starting point for making td.sh C (#2)
fix test for negative duration (#3)
add test for multiple duration and use %q to print out strings. resolve #4
add configure.scan -> configure.ac generated by audoscan
can be built with Autotools
separate library part, use auxiliary tools directory `build-aux`
set to C99, turn on warnings
fix error and warnings about getopt
add sprint_td function, print_td uses it with 64-char buffer

sprint_td somewhat mimics sprintf, for instance, returning the length.
use Check to unit test libtd

22 of 23 tests from td-test.sh can be tested using Check, the last one needs to test stdout. The benchmark would also need another way to perform.

AM_PROG_CC_C_O is added because Automake 1.13 still needs it, it's not required for 1.14+ according to the manual [1], AC_PROG_CC handles that.

[1]: www.gnu.org/software/automake/manual/html_node/Public-Macros.html
use Autotest to test multiple inputs
Merge branch 'c', update .gitignore, use top_buildir to link td

Conflicts:
	COPYING
	td-test.sh

* add benchmark recursive target to handle benchmarking
* td.sh unittest is done by Autotest
* move sub-directory gitignore entires to subdirs
* use top_builddir to link td

At this point, both implementations will be built and installed, can not be disabled by choices.