support :or together with :keys
Added complement
add a few tests for fn with destructuring.
Added some more usful functions

* some
* rest
* distinct
initial support for multimethods

mhh... this might be enough, or not. it does some things already,
though.
support default multimethods
Add multi-args for conj
- also add conj for Cons type
add instructions on how to get out of the repl without having to ctl-c
Merge pull request #92 from gigasquid/multi-arg-conj

Add multi-args for conj
Merge pull request #90 from heyLu/destructuring

Tiny destructuring fixes
Merge pull request #88 from thomasmulvaney/useful-funks

Useful funks

(complement, odd?, even?, distinct, some & rest)
implement -repr for most types
implement print, println, pr-str, pr and prn

print does not add a newline anymore, but println does. print also
inserts spaces between arguments now.
fix usages of print

that is, use println and don't add now extraneous spaces.
print values using -repr on the repl
add tests for str and -repr

and add -repr on symbols and fix pixie.test/show
implement -repr for Type
add ctl-d
Merge pull request #91 from heyLu/multimethods

Support for multimethods
Merge pull request #93 from gigasquid/repl-instructions

add instructions on how to get out of the repl without having to ctl-c