Add test for #17.
Prevent accidental creation of lexical closures.

Fixes #17. (Try async-test-7)
Have test file add its own directory to load path

This makes it so that one can do "emacs -batch -l async-test.el ..."
without having to also add "-l async.el -l async-file.el" at the
command line.
Add more comprehensive testing for anti-closure feature

Based on suggestions in
https://github.com/jwiegley/emacs-async/pull/18#issuecomment-26665920
More robust evaluation and closure-protection of start-func
Merge pull request #18 from DarwinAwardWinner/lexbind-fix

Lexbind fix
Add lexbind test
Add test for handling different ways of passing a function
Replace closure prevention with closure sanitation

"Sanitation" means that if a closure's list of lexical variables
contains any variables with unprintable values, those variables are
removed from the list. When async-debug is on, this also generates a
message about the removed variables.

This solution is arguably more hackish, but should also work in every
case where the "prevent all closures" solution worked as well as some
more cases.
Merge pull request #19 from DarwinAwardWinner/lexbind-fix

Lexbind fix redux
Complete the docstring for "async--get-function"
Merge pull request #21 from DarwinAwardWinner/lexbind-fix

Complete the docstring for "async--get-function"
Revert "* helm-async.el: Fix error handling."

This reverts commit 242ae734273162f4ec027618610a099c9a73557b.
Revert master back to 242ae73