Add Swap feature

src/tokens.h

@@ -20,12 +20,14 @@
 
 #include <stdint.h>
 
+#define MAX_TICKER_LEN 12 // 10 characters + ' ' + '\0'
+
 typedef struct tokenDefinition_t {
 #ifdef HAVE_CONTRACT_NAME_IN_DESCRIPTOR	
     uint8_t contractName[20];
 #endif    
     uint8_t address[20];
-    uint8_t ticker[12]; // 10 characters + ' \0'
+    uint8_t ticker[MAX_TICKER_LEN]; 
     uint8_t decimals;
 } tokenDefinition_t;