* more work on tukan compiler

* ccvm examples

* check-in ccvm demo

* removed `any`/`all`
* added `defined?` form

* topowalk with cc
* any/all evaluate lazily

* more work on emulating recursion in tukan
* more work on blue noise technique

* audio support, various language improvements

merge

* implemented toposorter in tukan

added randproj.sc

* added `let@` and `let:` forms for `do`

* native I/O support removes overhead between main loop and framework
* `do` supports simpler `fn` syntax

* syntax improvements; `do` permits returning multiple arguments, setting metacell

* `let` updates env per statement, entries are no longer keys
* `fn` body is implicit `let`

* support for launching native programs

* UVM: initial support for graphics

* improved repr output

* implemented comparison operators, eval, globals

* improved interpreter docs

* console based tukan interpreter is functional