Add namespaces to lisp

[vinc]

This PR introduces a lower level file namespace to the lisp allowing reading (file:read) and writing (file:write) directly from a file handle to have a better print function so the output of a script can now be redirected to a file from the shell for example.

This wasn't possible before:

lisp /tmp/lisp/pi.lsp 100 => pi.txt

The new notation using a dot . to group functions within a namespace will also be used for number, string, and regex with number.type, string.trim, and regex.match? for example.

[vinc]

New escaped tab \t and carriage return \r with the existing newline \n:

> (print "Hello,\tWorld!")
Hello,	World!
()

> (print "Hello,\rWorld!")
World!
()

> (print "Hello,\nWorld!")
Hello,
World!
()

[vinc]

> (mod -1 3)
2

> (rem -1 3)
-1

> (% -1 3)
-1

[vinc]

There are a few options for the namespace separator:

1. file::open
2. file:open
3. file.open
4. file/open

The first option :: is very common but so far I was thinking about using the second one : that is shorter. Both could be slightly confusing if I introduce keywords starting with a colon like :foo though.

A slash / would borrow the directory metaphor but might be confusing if the language is used as a shell whereas a dot . would work like it does for hostnames and filenames, for example: http.get "example.com/foo.txt".

[vinc]

If the language is used as a shell it might be interesting to rename read-file, write-file, and append-file to read, write, and append but the latter already exists.