AXSH_Tcl_OpenEngine() + AXSH_Tcl_EngineCommandProc() now static (no code change).
Prepare AXSH_Tcl_EngineCommandDeleteProc().
IDL: Remove "Vtbl" suffix from interface name, coclass name without initial "I".

* interface: ITclHostControlVtbl -> ITclHostControl
* coclass:   ITclHostControl     -> TclHostControl
Fix a bug in IActiveScriptSite::GetItemInfo() implementation.

* the two [out] pointers must be set to NULL when the corresponding flag is
    not set in dwReturnMask
* also removed the comment describing the method
Add axsh-testscript.tcl.
Check for NULL pointer in GetItemInfo(), add TODO comment.
Add TODO comment to 2 suspicious AddRef() calls in AXSH_InitHostControl().