Generate version header when configuring project

The basic idea is we create a version header template at
"src/base/version.h.in" and the build systems are expected to replace
strings that are enclosed with @ symbols and generate
"src/base/version.h" for other source files to consume/include.

src/gui/aboutdialog.cpp

@@ -32,6 +32,7 @@
 
 #include "base/unicodestrings.h"
 #include "base/utils/misc.h"
+#include "base/version.h"
 #include "ui_aboutdialog.h"
 #include "uithememanager.h"
 #include "utils.h"

src/gui/mainwindow.cpp

@@ -70,6 +70,7 @@
 #include "base/utils/fs.h"
 #include "base/utils/misc.h"
 #include "base/utils/password.h"
+#include "base/version.h"
 #include "aboutdialog.h"
 #include "addnewtorrentdialog.h"
 #include "autoexpandabledialog.h"

src/gui/programupdater.cpp

@@ -44,6 +44,7 @@
 #endif
 
 #include "base/net/downloadmanager.h"
+#include "base/version.h"
 
 namespace
 {