Added two new fuctions to dict API

[lgg2]

Hello,

I have added two new functions to iterate a dictionary without the use of a callback. I have also include a test purpose file.

Feel free to correct the changes. I think that are usefull.

P.D.: Sorry, I see in the commit that I have include the "test_mod" executable. Delete it.

Thanks.

[lgg2]

I'm not a full time programmer (only for hobby and some times for solve something in the work) and It is also my first "pull request" (also again in a very rudimentary way).

The reason for this two functions It is no need the use of a callback for each time that review for a dictionary keys.