Update Tcl/Tk to 8.6.4.
The new version of Tcl/Tk plays nice(r) with VS2015 CTP 6+.
diff --git a/PCbuild/tcltk.props b/PCbuild/tcltk.props
index f5a8643..96bd577 100644
--- a/PCbuild/tcltk.props
+++ b/PCbuild/tcltk.props
@@ -4,7 +4,7 @@
<PropertyGroup>
<TclMajorVersion>8</TclMajorVersion>
<TclMinorVersion>6</TclMinorVersion>
- <TclPatchLevel>3</TclPatchLevel>
+ <TclPatchLevel>4</TclPatchLevel>
<TclRevision>1</TclRevision>
<TkMajorVersion>$(TclMajorVersion)</TkMajorVersion>
<TkMinorVersion>$(TclMinorVersion)</TkMinorVersion>