* scl_memmgr supports both c and c++ memory management.
malloc, calloc, realloc and free for c.
new, delete operators for c++.
(in c++ files scl_memmgr.h should be included last because a macro
is used to replace new and delete with scl versions. If not included
last, this would break build.)
* Added scl_export.h with conditional flags for import/export.
* Added SCL_EXPRESS_EXPORT flag for all global variables in headers.
* Added SCL_EXPRESS_EXPORT flag for all function prototypes in headers.
* Added SCL_EXPRESS_DLL_EXPORTS flag for express CMakeLists.txt
davyw