[Zint-barcode] tcl binding for zint reformed

[Harald O. <har...@el...>]

Dear zint community,
the tcl binding for zint was reformed and braught up-to date.

Git Lost has maintained and build this before, thank you! You may continue.

I have removed the old MS-VC 6 makefile.

Instead, the current build system of Visual Studio is added.

I build like this:
- open the command prompt of visual studio
cd backend_tcl\win
nmake -f Makefile.vc TCLDIR=c:ltcl TKDIR=c:\tcl
while c:\tcl is the root of a tcl distribution.
nmake -f Makefile.vc TCLDIR=c:ltcl TKDIR=c:\tcl install 
INSTALLDIR=c:\test\zinttcl

It should take the checkout id of git and compile it into the binary. 
The command zint::build-info should return this.
For me, it did not work. But I am a hyper-novice with git and don't 
understand anything.

When the library is unloaded, the commands are destroyed now.
Before, the interpreter crashed, when "zint" was executed with unloaded 
library.
This is only half of the solution, as within tcl, commands may be 
renamed. In this case, it will not work.
But that are two unlikely actions: unload and rename the command.

Hope you like the change.
Please come back to me early, if something does not work.
It is for sure ME !

Thanks for all,
Harald