[nem-en] Bugs in extension method implementation

[vc]

   > Indeed, it fails with current boot/ version, but it works correctly
   > with out.stage3/ before your commit.
   
   I not use boot/ncc.exe. I use compiled version of compiler. But I compile
it using MSBuild (Nemerle.sln).
   
   > Well, this is strange, unless you compile using one compiler, but
   > referencing the other one, like:
   > boot/ncc.exe  utility.n -r out.stage3/Nemerle.Compiler
   
   Probably it occurs because I compile a code from VS 2005.
   
   > Could you try again with the version before patch and tell me how
   > exactly do I reproduce this error?
   
   This is compilation log obtained from VS 2005.
   -----------------------------------------------------
   Target CoreCompile:
   C:\Program Files\Nemerle\ncc.exe /no-color /nowarn:1701,1702 /no-stdlib
   /define:DEBUG;TRACE /debug+ 
   /out:obj\Debug\Ext2.exe 
   /target:exe Properties\AssemblyInfo.n Main.n 
   /ref:"C:\Program Files\Nemerle\Nemerle.Compiler.dll" 
   /ref:"C:\Program Files\Nemerle\Nemerle.dll" 
   /ref:C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.Data.dll 
   /ref:C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.dll 
   /ref:C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.Xml.dll
   
   D:\MyProjects\Tests\Nemerle\Ext2\Ext2\Main.n(5,14,5,28): error : there is
no member named `GetName' in Nemerle.Compiler.IMember with type ?
   -----------------------------------------------------
   C:\Program Files\Nemerle\ contains compilers binaries r6576 (compiled
from source, not boot).
   
   > I don't like the patch, since IsDefined against assembly loaded into
   > SystemTypeCache is the *correct* (and probably fastest) way  to check
   > for attributes.
   
   In my option ExtensionAttribute not usual attribute. As to speed... I do
not think, that it will affect performance. Not many of classes containing
extension methods. Against a background of time of loading of metadata it's
are nothing.