DOC(readme) DROP txt file with outdated dev-help >

keep just the `README.md`file with user-facing help,
not to confuse them.

README.txt

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-COMPILING VECTO
----------------
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-Compiling VECTO requires Microsoft Visual Studio 2013 (or later)
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-Option 1: Compiling from the command-line
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-you can build VECTO using the following command:
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-"c:\Program Files (x86)\MSBuild\14.0\Bin\MSBuild.exe" Vecto.sln /t:Build /p:Configuration=Release
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-or
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-"c:\Program Files (x86)\MSBuild\14.0\Bin\MSBuild.exe" Vecto.sln /t:Build /p:Configuration=Debug
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-"C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\amd64\MSBuild.exe"
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-Option 2: Load the solution file in Visual Studio and compile VECTO.
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-The executable can be found in 
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-<Path to VECTO-Source Folder>\VECTO\bin\Release 
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-or
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-<Path to VECTO-Source Folder>\VECTO\bin\Debug
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-depending on the configuration.
\ No newline at end of file