sqlite backend: made it possible to compile out-of-tree

config.h is now only included if HAVE_CONFIG_H is set.
ENABLE_SQLITE can be set via -D instead.

Removed inclusion of "test.h" and "syncevo/Logging.h",
we don't install it.

Moved header files around so that they are only
included when needed.

Added a README with compile instructions.

src/backends/sqlite/README

@@ -0,0 +1,28 @@
+This is a demo backend. It uses a database schema that is similar to
+the one used on the iPhone, but it is not as complete.
+
+To compile this backend as part of SyncEvolution, configure with
+--enable-sqlite.
+
+To compile it against a binary distribution of SyncEvolution, make
+sure that the SyncEvolution, Synthesis and sqlite developer files are
+installed and that pkg-config can find syncevolution.pc, synthesis.pc
+and sqlite.pc. Set your PKG_CONFIG_PATH if necessary.
+
+Then the source files can be compiled as follows:
+   g++ -fpic -DPIC -DENABLE_SQLITE -shared -I. \
+       `pkg-config --cflags --libs syncevolution`
+       `pkg-config --cflags --libs sqlite`
+       *.cpp  \
+       -o /tmp/syncsqlite.so
+
+Install /tmp/syncsqlite.so by moving it into the
+"lib/syncevolution/backends" directory of the SyncEvolution
+installation.
+
+It then should show up as additional choice for the "type" property:
+   syncevolution --source-property type=?
+
+   ...
+   SQLite Address Book = addressbook = contacts = sqlite-contacts
+      vCard 2.1 (default) = text/x-vcard

src/backends/sqlite/SQLiteContactSource.cpp

@@ -18,15 +18,17 @@
  * 02110-1301  USA
  */
 
-#include "config.h"
-#include <syncevo/Logging.h>
-#include <syncevo/SynthesisEngine.h>
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
 
 #include <synthesis/SDK_util.h>
 #ifdef ENABLE_SQLITE
 
 #include "SQLiteContactSource.h"
 
+#include <syncevo/SynthesisEngine.h>
+#include <synthesis/sync_dbapi.h>
 
 #include <algorithm>
 #include <cctype>

src/backends/sqlite/SQLiteContactSourceRegister.cpp

@@ -19,7 +19,11 @@
  */
 
 #include "SQLiteContactSource.h"
-#include "test.h"
+
+#ifdef ENABLE_UNIT_TESTS
+# include <cppunit/extensions/TestFactoryRegistry.h>
+# include <cppunit/extensions/HelperMacros.h>
+#endif
 
 static SyncSource *createSource(const SyncSourceParams &params)
 {

src/backends/sqlite/SQLiteUtil.cpp

@@ -17,7 +17,9 @@
  * 02110-1301  USA
  */
 
-#include "config.h"
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
 
 #ifdef ENABLE_SQLITE