fix/send normal output to stderr

[kjuulh]

This pr redirects all output to be send via. stderr in ui.UI instead of stdout.

Stdout is supposed to be used for programs which should pipe to other programs.

Stderr, is supposed to be used for giving information to the user about the process. As such I've taken the libery of changing the shell.go exec from Errorln -> Infoln. This should remove the red text, as the output is technically not an error.

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@kjuulh :
what are stdout and stderr supposed to be used for?

chatgpt:
stdout (standard output) and stderr (standard error) are two separate output streams used in computer programming, especially in Unix-like operating systems. They serve different purposes:

1. stdout (Standard Output): This is the default output stream for data (like text) that a program is designed to produce. In most cases, this data is the main output of the program. For example, if you run a program to calculate something, the result of the calculation would be sent to stdout.
2. stderr (Standard Error): This is used specifically for outputting error messages and diagnostics. It's separate from `stdout so that error messages can be handled differently. For example, in a logging system, you might want to capture errors separately from regular output for debugging purposes.

Separating these streams allows for more flexible handling of output. For instance, in a Unix command line, you can redirect stdout to a file, while still viewing stderr on the terminal, or vice versa. This separation is useful in debugging and log management in software development.