wrap all library code into namespace if VCMI_LIB_NAMESPACE is defined

preparation for having client and server in a single process

lib/rmg/RmgArea.cpp

@@ -12,6 +12,8 @@
 #include "RmgArea.h"
 #include "CMapGenerator.h"
 
+VCMI_LIB_NAMESPACE_BEGIN
+
 namespace rmg
 {
 
@@ -402,3 +404,5 @@ bool operator== (const Area & l, const Area & r)
 }
 
 }
+
+VCMI_LIB_NAMESPACE_END