Sheetjs: Windows build

[SheetJSDev]

Simplify the build and test process to enable a Windows development workflow

see https://github.com/SheetJS/js-harb/issues/7 h/t @simon-p-r

[simon-p-r]

Happy to help with any testing!

[SheetJSDev]

@simon-p-r starting from a fresh windows setup we were able to build the source and run the tests!

https://github.com/sheetjs/js-xlsx#windows is the relevant part of the documentation.

Configuration Steps:

1) git clone https://github.com/SheetJS/js-xlsx/
2) download the test files snapshot https://github.com/SheetJS/test_files/releases/download/20170409/test_files.zip
3) extract that to the test_files subdirectory in the source tree
4) npm install -g mocha and npm install

After making changes to the bits files, make.cmd will rebuild xlsx.js and mocha -t 30000 will run tests.

[simon-p-r]

I will have a go and let you know if there are any problems

[reviewher]

@simon-p-r updated the make.cmd script to streamline the process. Tested on an old Surface Pro 3 running windows 8.1 and everything seemed to work! Since we aren't using any powershell features it should work back to Windows 7.

Preparation:

• Install node (6.10.2 in this test but other versions work too)
• Install git windows (2.12.2.2 in this test), use default options (core.autocrlf = true)
• Download the test files release from the test_files repo

Commands:

• make init to install dependencies and dev modules
• make will build the source
• make lint will run the linter
• make misc will run a small set of tests
• make test will run the full tests
• make book will update the README from the docbits.