The libsynthesis_3.4.0.47+syncevolution-1-3-99-7-20140203 tag
accidentally matched the check for a non-exact-tag "git-describe"
output (-<number of changes>-g<hash>). Therefore the actual tags
weren't even checked.
Reversing the check such that we look at tags ourselves and proceed with
them if one matches avoids this problem.
All but toplevel Makefile.am are replaced with their non-recursive
counterparts. The generation of configure.in was removed (and thus
configure-{pre,post}.in are also removed) in favor of configure.ac
and m4 macros adding backend specific configure parts.
Version number is generated like in old build system.
There are still many things to improve, but for now there are no
immediate regressions. AUTOTOOLS-TODO contains a list of possible
improvements and fixes. AUTOTOOLS-TESTING contains what was tested
with current build system (configure flags, make options).