Add/allow arguments in commands

[elkinaguas]

This pull request adds support for arguments in commands.

To add an argument to a command, just add un underscore in front of the argument. When you run the command with clir, it will ask you to input the commands you specified.

Example:
commad : echo _text ; echo _text2 ; echo text3

Prompt after running the command with clir:

Enter value for '_text': hola
Enter value for '_text2': mundo
Running command: echo hola ; echo mundo ; echo text3
hola
mundo
text3