Added "continuous logging" functionality.

This is useful if you're having stability troubles and/or are worried
about crashes. With traditional logging you can lose your capture if
the program, CAN adapter, or computer crash before you've saved. With
continuous logging the file is flushed to disk every couple of seconds
so you won't lose more than a few seconds of log even during a crash.

ui/mainwindow.ui

@@ -49,6 +49,24 @@
     </item>
     <item>
      <layout class="QVBoxLayout" name="verticalLayout">
+      <item>
+       <widget class="QLabel" name="lblContMsg">
+        <property name="font">
+         <font>
+          <pointsize>11</pointsize>
+          <weight>75</weight>
+          <italic>true</italic>
+          <bold>true</bold>
+         </font>
+        </property>
+        <property name="text">
+         <string/>
+        </property>
+        <property name="alignment">
+         <set>Qt::AlignCenter</set>
+        </property>
+       </widget>
+      </item>
       <item alignment="Qt::AlignHCenter">
        <widget class="QLabel" name="label">
         <property name="sizePolicy">
@@ -240,6 +258,8 @@
     <addaction name="actionOpen_Log_File"/>
     <addaction name="actionSave_Filtered_Log_File"/>
     <addaction name="actionSave_Log_File"/>
+    <addaction name="actionSave_Continuous_Logfile"/>
+    <addaction name="separator"/>
     <addaction name="separator"/>
     <addaction name="actionLoad_Filter_Definition"/>
     <addaction name="actionSave_Filter_Definition"/>
@@ -428,6 +448,11 @@
     <string>Signal Viewer</string>
    </property>
   </action>
+  <action name="actionSave_Continuous_Logfile">
+   <property name="text">
+    <string>Start Continuous Logging</string>
+   </property>
+  </action>
  </widget>
  <layoutdefault spacing="6" margin="11"/>
  <resources/>