Added is{scalar,value,..}. Fixes leaf_paths bug.

[alex-ozdemir]

Now paths to false leaves are correctly returned.
Added the new test functions to the docs.

[alex-ozdemir]

This is a partial solution to #1163.

[coveralls]

Coverage increased (+0.07%) to 85.402% when pulling dc9d437 on alex-ozdemir:master into 0b82185 on stedolan:master.

[ghost]

I proposed something very similar a long time ago. I like it! I find myself using type == "array" more often than arrays.

[coveralls]

Coverage increased (+0.5%) to 85.839% when pulling 22a0a67 on alex-ozdemir:master into 0b82185 on stedolan:master.

[coveralls]

Coverage remained the same at 85.333% when pulling c87889e on alex-ozdemir:master into 0b82185 on stedolan:master.

[alex-ozdemir]

Okay, paths to null handled by fixing paths. The fix uses an alternative behavior for recurse. I chose not to include this new behavior in the stdlib, as having two floating around would probably just confuse people.

This PR now completely closes #1163.

[coveralls]

Coverage remained the same at 85.333% when pulling cc573c4 on alex-ozdemir:master into 0b82185 on stedolan:master.

[nicowilliams]

Thanks! I'll review.

[alex-ozdemir]

Paging @nicowilliams 😄