Move all core-functionality to subsurface-core

And adapt a new CMakeLists.txt file for it. On the way I've also
found out that we where double-compilling a few files. I've also
set the subsurface-core as a include_path but that was just to
reduce the noise on this commit, since I plan to remove it from
the include path to make it obligatory to specify something like

 include "subsurface-core/dive.h"

for the header files. Since the app is growing quite a bit we ended
up having a few different files with almost same name that did
similar things, I want to kill that (for instance Dive.h, dive.h,
PrintDive.h and such).

Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

subsurface-core/gettextfromc.cpp

@@ -0,0 +1,27 @@
+#include <QCoreApplication>
+#include <QString>
+#include <gettextfromc.h>
+
+const char *gettextFromC::trGettext(const char *text)
+{
+	QByteArray &result = translationCache[QByteArray(text)];
+	if (result.isEmpty())
+		result = translationCache[QByteArray(text)] = trUtf8(text).toUtf8();
+	return result.constData();
+}
+
+void gettextFromC::reset(void)
+{
+	translationCache.clear();
+}
+
+gettextFromC *gettextFromC::instance()
+{
+	static QScopedPointer<gettextFromC> self(new gettextFromC());
+	return self.data();
+}
+
+extern "C" const char *trGettext(const char *text)
+{
+	return gettextFromC::instance()->trGettext(text);
+}