build now works with --srcdir=../a/relative/path, --srcdir=/an/absolute/one
and in source. Auxiliary data in data and test/testdata is generated by new
Makefiles in these directories (data is new inside source). Some cleanup is
still needed, for example when makeconv generates test files... Test code
now knows about out of source vs in source build. Sorry... (Will be fixed
if data and source are at the same level some day.)
X-SVN-Rev: 2373
