Better project files.

- Output directly to rel\ instead of to bin\ and then copying files over.
- Deduped Win32 vs x64 configs
- Moved some common properties to hexchat.props
- All build intermediates (except htm's intermediates) are no longer emitted in the source directory

src/common/common.vcxproj.filters

@@ -71,10 +71,10 @@
     <ClInclude Include="text.h">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="textenums.h">
+    <ClInclude Include="$(HexChatLib)textenums.h">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="textevents.h">
+    <ClInclude Include="$(HexChatLib)textevents.h">
       <Filter>Header Files</Filter>
     </ClInclude>
     <ClInclude Include="tree.h">
@@ -98,13 +98,13 @@
     <ClInclude Include="hexchat-plugin.h">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="..\..\config.h">
+    <ClInclude Include="$(HexChatLib)config.h">
       <Filter>Header Files</Filter>
     </ClInclude>
     <ClInclude Include="typedef.h">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="marshal.h">
+    <ClInclude Include="$(HexChatLib)marshal.h">
       <Filter>Header Files</Filter>
     </ClInclude>
     <ClInclude Include="plugin-identd.h">
@@ -181,7 +181,7 @@
     <ClCompile Include="hexchat.c">
       <Filter>Source Files</Filter>
     </ClCompile>
-    <ClCompile Include="marshal.c">
+    <ClCompile Include="$(HexChatLib)marshal.c">
       <Filter>Source Files</Filter>
     </ClCompile>
     <ClCompile Include="plugin-identd.c">