"Exec"-like instruction

[TrevorBrunette]

As a program user
I want an additional instruction which can run a command on the system natively
So that I can interact with the user environment.

Request Description
Implement an instruction that executes a given command natively. Perhaps it will also be worthwhile to implement utility instructions that can get information about the operating system so that multi-platform code can be made. Also add documentation for this instruction in the wiki.

e.g., exec $t0 "cat hello world"

1. Executes cat 'hello world' on the system
2. Creates a string in memory representing the standard output from that command
3. Stores a pointer to the string created in (2) and stores it into the specified register, $t0 here