Doxygen only knows how to call dot with -Tpng, while using
-Tpng:gd produces pictures that are 10 times smaller.  Use a
simple wrapper around dot to simplify this.

* doc/dot.in: New file, that wrap the system's dot and replace
-Tpng by -Tpng:gd.
* doc/Makefile.am ($(srcdir)/stamp): Depend on dot.
* doc/Doxyfile.in: Update to 1.6.2.
(DOT_PATH): Set to @srcdir@ to use doc/dot instead of the
system's dot.
* configure.ac: Find the absolute path of dot, and generate
the doc/dot script.

* src/sanity/style.test: Check for missing Copyrights blurbs.
* src/sanity/Makefile.am: Run style.test before includes.test.
* iface/gspn/dcswave.test, iface/gspn/dcswaveeltl.test,
iface/gspn/dcswavefm.test, iface/gspn/dcswaveltl.test,
iface/gspn/simple.test, iface/gspn/udcsefm.test,
iface/gspn/udcseltl.test, iface/gspn/udcsfm.test,
iface/gspn/udcsltl.test, iface/nips/nipstest/dotty.test,
iface/nips/nipstest/emptiness.test, src/eltltest/acc.test,
src/eltltest/nfa.test, src/saba/sabacomplementtgba.cc,
src/sabatest/sabacomplementtgba.cc, src/tgbatest/eltl2tgba.test,
src/tgbatest/taatgba.test: Add missing Copyright blurb.