Map string packages

[filipefilardi]

Map string packages and find related functions

[blmayer]

I think this fits in issue #3. We should close this.

[filipefilardi]

We're still missing functions to find patterns in string and other stuff non related to cast to string. I think we should map not only the packages but also related functions before closing this issue. WYT?

[blmayer]

I think that's another subject, but we can find more functions on this one, and do a separate study for pattern matching.