Allow 'new Function' for _.arity.
Rework _.unfold for clarity and to avoid JSHint warning W093.

W093 is 'Did you mean to return a conditional instead of an assignment?"
Avoid JSHint warning W093 in _.accumulate.
Prevent JSHint warning W093.
Use === for comparing against 'true' and '0'.
Don't assign to arguments object. JSHint E031
Don't assign to .
Don't assign to undefined.
Break compound statement apart. JSHint W030
Fixed misplaced parenthesis.
Allow 'weird' construction for isPlainObject test.
Fix bad line breaking in ternary. JSHint W014
Use object literal notation. JSHint W10
Merge pull request #82 from joshuacc/jshint

Fixed remaining JSHint warnings and errors