fix readme typo (when -> with)
Merge pull request #422 from mourner/patch-1

Fix readme typo (when -> with)
Simplify nested conditionals if possible
Merge pull request #424 from mattbasta/simplify_conditionals

Simplify nested conditionals if possible
Add option `keep_fargs`.

By default it's `false`.  Pass `true` if you need to keep unused function
arguments.

Close #188.
Mangle name of exception when --screw-ie8.  Fix #430.

The effect of not mangling it was visible only with --screw-ie8 (otherwise
the names would be mangled exactly because they leaked into the parent
scope).