psci: validate imports when using :i

fixes #609
Fix #611 - do not take locally-bound names into account when calculating binding groups
Fix #624 - remove xdg-basedir dependency, simplify build.
validate imports correctly
Merge pull request #637 from purescript/624

Fix #624 - remove xdg-basedir dependency, simplify build.
Merge pull request #636 from purescript/611

Fix #611 - do not take locally-bound names into account when calculating...
Merge pull request #635 from Bogdanp/master

psci: validate imports when using :i
Remove --runtime-type-checks
Update docs
Merge pull request #639 from purescript/no-runtime-type-checks

Remove --runtime-type-checks
Move typeCheckModule to TypeChecker
Check exported members don't use private classes
Check classes aren't partially exported
Reduce forM_ duplication
Merge pull request #640 from purescript/check-exports

Check exports
Initial work on Mac build and install scripts #468
Modify bundle script to work on Linux
+ initial version of new docgen
= types refactoring
+ completely rewritten markdown backend
= improved doc extraction
= use blockquotes for docstrings in Markdown backend