Update bitcoinapi.h

Author: minium

src/bitcoinapi/bitcoinapi.h

@@ -61,7 +61,7 @@ class BitcoinAPI
 
     void keypoolrefill();
     bool settxfee(double amount);
-    double estimatefee(uint8_t blocks);
+    double estimatefee(int blocks);
 
     std::string signmessage(const std::string& bitcoinaddress, const std::string& message);
     bool verifymessage(const std::string& bitcoinaddress, const std::string& signature, const std::string& message);