move most explicit getters in optionsmodel to header

- is more consistent and saves quite some lines of code

src/qt/optionsmodel.cpp

@@ -262,23 +262,3 @@ qint64 OptionsModel::getTransactionFee()
 {
     return nTransactionFee;
 }
-
-bool OptionsModel::getMinimizeToTray()
-{
-    return fMinimizeToTray;
-}
-
-bool OptionsModel::getMinimizeOnClose()
-{
-    return fMinimizeOnClose;
-}
-
-int OptionsModel::getDisplayUnit()
-{
-    return nDisplayUnit;
-}
-
-bool OptionsModel::getDisplayAddresses()
-{
-    return bDisplayAddresses;
-}

src/qt/optionsmodel.h

@@ -44,10 +44,10 @@ public:
 
     /* Explicit getters */
     qint64 getTransactionFee();
-    bool getMinimizeToTray();
+    bool getMinimizeToTray() { return fMinimizeToTray; }
-    bool getMinimizeOnClose();
+    bool getMinimizeOnClose() { return fMinimizeOnClose; }
-    int getDisplayUnit();
+    int getDisplayUnit() { return nDisplayUnit; }
-    bool getDisplayAddresses();
+    bool getDisplayAddresses() { return bDisplayAddresses; }
     QString getLanguage() { return language; }
 
 private: