Check-in [6fc9ac29eb]

# Rationale

Users that are creating interpreters are often getting errors because they are getting the `Tcl_CreateInterp` macro.
This error is a runtime null pointer exception which several users find confusing.
The user as to be astute enough to follow instructions and see that `USE_TCL_STUBS` will replace a C function call with a macro.
By providing a plain function, the users can have a easier time embedded interperters and using stubs.

```
/usr/local/include/tcl8.6/tclDecls.h:#define Tcl_CreateInterp \
/usr/local/include/tcl8.6/tclDecls.h- (tclStubsPtr->tcl_CreateInterp) /* 94 */
```

# Specification

There will be a new function in `libtclstub??.a` that always performs interpreter initialization and stub table initialization.
The signature is **Tcl\_CreateInterpWithStubs**(const char \*_version_, int _exact_).
The _version_ and _exact_ parameters match `Tcl_InitStubs`.

On error NULL is returned instead of a TCL interpreter.
Without this pointer there is no way to obtain extended error codes, but the trade off is that it makes the API much easier to use.
(That could be an error, someone could clarify that for me.)

## Example Implementation

``` 
/* must be compiled without stubs */

#undef USE_TCL_STUBS
#include <tcl.h>

Tcl_Interp *
Tcl_CreateInterpWithStubs(
    const char *version,
	int exact)
{
    Tcl_Interp *interp = Tcl_CreateInterp();

    if (Tcl_Init(interp) == TCL_ERROR ||
            Tcl_InitStubs(interp, version, exact) == NULL ||
            Tcl_PkgRequire(interp, "Tcl", version, exact) == NULL) {
        return NULL;
    }

    return interp;
}
```

# Implementation

Please refer to the `tip-???` branch of the core Tcl repository.

# Backwards Compatibility

This is a new function in the TCL C API.

# Copyright

This document has been placed in the public domain.

# Rationale

Users that are creating interpreters are often getting errors because they are getting the `Tcl_CreateInterp` macro.
This error is a runtime null pointer exception which several users find confusing.
The user as to be astute enough to follow instructions and see that `USE_TCL_STUBS` will replace a C function call with a macro.
By providing a plain function, the users can have a easier time embedded interperters and using stubs.


    /usr/local/include/tcl8.6/tclDecls.h:#define Tcl_CreateInterp \
    /usr/local/include/tcl8.6/tclDecls.h- (tclStubsPtr->tcl_CreateInterp) /* 94 */


# Specification

There will be a new function in `libtclstub??.a` that always performs interpreter initialization and stub table initialization.
The signature is **Tcl\_CreateInterpWithStubs**(const char \*_version_, int _exact_).
The _version_ and _exact_ parameters match `Tcl_InitStubs`.

On error NULL is returned instead of a TCL interpreter.
Without this pointer there is no way to obtain extended error codes, but the trade off is that it makes the API much easier to use.
(That could be an error, someone could clarify that for me.)

## Example Implementation


    /* must be compiled without stubs */

    #undef USE_TCL_STUBS
    #include <tcl.h>

    Tcl_Interp *
    Tcl_CreateInterpWithStubs(
        const char *version,
        int exact)
    {
        Tcl_Interp *interp = Tcl_CreateInterp();

        if (Tcl_Init(interp) == TCL_ERROR ||
                Tcl_InitStubs(interp, version, exact) == NULL ||
                Tcl_PkgRequire(interp, "Tcl", version, exact) == NULL) {
            return NULL;
        }

        return interp;
    }


# Implementation

Please refer to the `tip-???` branch of the core Tcl repository.

# Backwards Compatibility

This is a new function in the TCL C API.

# Copyright

This document has been placed in the public domain.