test/SerializationTest.vala: temporarily switch back from clear_caches to clear_cache to prevent API break
examples/c: add c examples
test/SerializableTest.vala: temporarily revert clear_changes namefix to avoid breaking API for 0.3.2
Revert "examples/c: add c examples"

This reverts commit 92d1d44cd5f11a9fe0f629d8c2ee50f8c033a5a9.
examples: rename Makefiles for c and vala to avoid collision with automake
examples: add Makefile.am files so we can catch examples in make distcheck
examples/vala/Makefile.am: EXTRA_DIST, not EXTRA_FILES
configure.ac, Makefile.am: make sure examples/ is included in make distcheck