[Qt] extend validate line edit and btc address validator

- remove btc address length from address validator
- add an optional btc address check in validated line edit that defaults
  to off and is used in GUIUtil::setupAddressWidget()
- an isAcceptable() check is added to validated line edit on focus out
  which only kicks in, when a validator is used with that widget
- remove an isAcceptable() check from sendcoinsentry.cpp
- remove obsolete attributes from ui files, which are set by calling
  GUIUtil::setupAddressWidget()
- move some more things to GUIUtil::setupAddressWidget() and remove them
  from normal code e.g. placeholder text

src/qt/qvalidatedlineedit.cpp

@@ -4,10 +4,13 @@
 
 #include "qvalidatedlineedit.h"
 
+#include "bitcoinaddressvalidator.h"
 #include "guiconstants.h"
 
 QValidatedLineEdit::QValidatedLineEdit(QWidget *parent) :
-    QLineEdit(parent), valid(true)
+    QLineEdit(parent),
+    valid(true),
+    checkValidator(0)
 {
     connect(this, SIGNAL(textChanged(QString)), this, SLOT(markValid()));
 }
@@ -34,11 +37,20 @@ void QValidatedLineEdit::focusInEvent(QFocusEvent *evt)
 {
     // Clear invalid flag on focus
     setValid(true);
+
     QLineEdit::focusInEvent(evt);
 }
 
+void QValidatedLineEdit::focusOutEvent(QFocusEvent *evt)
+{
+    checkValidity();
+
+    QLineEdit::focusOutEvent(evt);
+}
+
 void QValidatedLineEdit::markValid()
 {
+    // As long as a user is typing ensure we display state as valid
     setValid(true);
 }
 
@@ -47,3 +59,49 @@ void QValidatedLineEdit::clear()
     setValid(true);
     QLineEdit::clear();
 }
+
+void QValidatedLineEdit::setEnabled(bool enabled)
+{
+    if (!enabled)
+    {
+        // A disabled QValidatedLineEdit should be marked valid
+        setValid(true);
+    }
+    else
+    {
+        // Recheck validity when QValidatedLineEdit gets enabled
+        checkValidity();
+    }
+
+    QLineEdit::setEnabled(enabled);
+}
+
+void QValidatedLineEdit::checkValidity()
+{
+    if (text().isEmpty())
+    {
+        setValid(true);
+    }
+    else if (hasAcceptableInput())
+    {
+        setValid(true);
+
+        // Check contents on focus out
+        if (checkValidator)
+        {
+            QString address = text();
+            int pos = 0;
+            if (checkValidator->validate(address, pos) == QValidator::Acceptable)
+                setValid(true);
+            else
+                setValid(false);
+        }
+    }
+    else
+        setValid(false);
+}
+
+void QValidatedLineEdit::setCheckValidator(const QValidator *v)
+{
+    checkValidator = v;
+}