Add shell aliases

[vinc]

No description provided.

[vinc]

Example of shell session:

> /tmp

> env
TZ    "7200"
DIR   "/tmp"
HOME  "/usr/vinc"

> env FOO "Hello, World!" # Set env var and shell var

> env FOO
Hello, World!

> env
TZ    "7200"
DIR   "/tmp"
HOME  "/usr/vinc"
FOO   "Hello, World!"

> print $FOO
Hello, World!

> set foo "Hi there" # Set shell var

> alias p "print"

> p $foo
Hi there

> unset foo # Unset shell var

> unset FOO # Unset env var and shell var

> unalias p # Remove command alias

TODO: env will have to be reimplemented as a builtin command to set shell variables, and $DIR is not yet an env var.

[vinc]

Some aliases are present in /ini/shell.sh but commented out to offer an experience closer to Unix. This would add ls /tmp instead of list /tmp or it's alias l /tmp for example.

Some commands could also be removed, for example list /tmp is equivalent to read /tmp, the only differences being the error message when trying to read a file or device, and automatically listing the current directory when invoked without arguments. Another case is goto /tmp, aliased to g /tmp and go /tmp that has a shorter equivalent with simply /tmp. And finally quit with its alias q have become the main way to quit a program so exit could be moved to the Unix compatibility aliases because the shortcut e is already taken by edit.