v1.6.1

Public release of the GetNuTool v1.6.1

* FIXED: Fixed problem "Input string was not in a correct format" when used version with release type,
         e.g.: 1.2.3-alpha, 1.2.3-beta-2, 1.2.3-rc ...

* FIXED: Avoids errors with possible incorrect CRC & Compressed size info. Issue #3
* FIXED: Fixed problems with paths and whitespace characters for `-unpack` command in executable version.
* CHANGED: Removed '15.0' from searching by registry key as an unused way for all new VS2017+
* CHANGED: 'MSBuild was not found' now returns (0x2) ERROR_FILE_NOT_FOUND
* CHANGED: Сhanged variable name %msbuild% to %msbuildexe% that was related for Issue #2
* CHANGED: Improved comparing arguments for executable version.