Added plugin support for drawing messages to screen.

- Either a single string will be drawn to screen, or nothing will be drawn.
 - Intelligently registers and unregisters drawing callback to minimize overhead when no message is being displayed.
 - Currently does not support newline characters (\r or \n). Newlines will cause text to be drawn overlapped.

xpcPlugin/xpcPlugin/xpcPlugin.vcxproj

@@ -97,10 +97,12 @@
   </ItemDefinitionGroup>
   <ItemGroup>
     <ClInclude Include="..\..\C\src\xplaneConnect.h" />
+    <ClInclude Include="..\xpcDrawing.h" />
     <ClInclude Include="..\xpcPluginTools.h" />
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\..\C\src\xplaneConnect.c" />
+    <ClCompile Include="..\xpcDrawing.cpp" />
     <ClCompile Include="..\XPCPlugin.cpp" />
     <ClCompile Include="..\xpcPluginTools.cpp" />
   </ItemGroup>

xpcPlugin/xpcPlugin/xpcPlugin.vcxproj.filters

@@ -21,6 +21,9 @@
     <ClInclude Include="..\xpcPluginTools.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="..\xpcDrawing.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\..\C\src\xplaneConnect.c">
@@ -32,6 +35,9 @@
     <ClCompile Include="..\xpcPluginTools.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="..\xpcDrawing.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <Library Include="..\SDK\Libraries\Win\XPLM.lib">