Export symbols in order to support shared libraries (#54)

* Add BAC_ROUTING compile definition

* Reorder cmake

* Fix OpenSSL support: support both 1.0 and 1.1t pus

* Explicitly export symbols, hidden by default

* Build shared libraries on travis using cmake

* Learn Makefile about static library

* Fix build using mingw with cmake

* Do not cleanup twice or after potential free

src/bacnet/bacpropstates.h

@@ -26,6 +26,7 @@
 
 #include <stdint.h>
 #include <stdbool.h>
+#include "bacnet/bacnet_stack_exports.h"
 #include "bacnet/bacenum.h"
 #include "bacnet/bacapp.h"
 #include "bacnet/timestamp.h"
@@ -71,15 +72,18 @@ typedef struct {
 extern "C" {
 #endif /* __cplusplus */
 
+    BACNET_STACK_EXPORT
     int bacapp_decode_property_state(
         uint8_t * apdu,
         BACNET_PROPERTY_STATE * value);
 
+    BACNET_STACK_EXPORT
     int bacapp_decode_context_property_state(
         uint8_t * apdu,
         uint8_t tag_number,
         BACNET_PROPERTY_STATE * value);
 
+    BACNET_STACK_EXPORT
     int bacapp_encode_property_state(
         uint8_t * apdu,
         BACNET_PROPERTY_STATE * value);