Funz plugin: Excel

This plugin is dedicated to launch Excel calculations from Funz. It supports the following syntax and features:

Input
- file type supported: '.xlsx' or '.xlsm'
- parameter syntax:
  - variable syntax: $(...)
  - formula syntax: @{...}
  - comment char: #
- example input file: sheet.xlsx
  - will identify input cell commented by $VariableName as variables
Output
- file type supported: 'out.txt' (which is standard output stream)
- read any commented cell =ResultName
- example output file:
```
Microsoft (R) Windows Script Host Version 5.8
Copyright (C) Microsoft Corporation. All rights reserved.

z=125
```
  - will return output:
    - z=125