create a magnolisp/2014 language

and have magnolisp proper not export racket/base for phase level 0
define #%magnolisp in a new core.rkt module

which is for Magnolisp core language definitions,
as opposed to macro-defined "concrete" syntax
make 'put-int' yield its argument

so can wrap any expr for its side effect
`fn` -> `->`
have a separate `putting-int` expression

so `put-int` can remain a procedure
`do` -> `begin-return`
document magnolisp/core module
more 'CORE' to core.rkt
name the 'in-racket annotating forms differently

in an easier-to-remember way
separate reader-ext for 2014 as well
remove 'anno' form

seems like a needless indirection
remove `let-var`
switch from #:annos to #:: (and with splicing syntax)

also, remove #an reader extension which now seems redundant
adjust docs to use #:: and not to use #an
add note about language differences in examples into docs