Merge pull request #14 from jdegoes/externs-fix

Externs fix
Don't export Cofree constructor

No longer necessary as `psc` outputs externs files with kind annotations
for type constructors now
Implement `go` directly
Implement `resume` directly
Implement `goEff` directly
Revert "Implement `goEff` directly"

This reverts commit 08112dae61ecac973222eb3b56793cc68b73f52f.
Merge pull request #16 from purescript-contrib/avoid-ffi

Avoid ffi
Merge pull request #15 from purescript-contrib/cofree-export-fixed

Don't export Cofree constructor
Update build and package files
merge