Overwrite behavior

[qlixed]

Currently I simply overwrite the buffer and nothing else. This is done in this way to avoid memory leaks and other kind of issues that might appear if i change the object buffer size, this leads us to get the '\0x0\0x0...' string.
With this in mind, here is some ideas about the current situation:

• Make a overwrite-and-get-new-string: So we get a correct "empty" string: "". This might add an extra decrement of the reference of the object.
• Let the '\0x0...' format as a kind-of-debug option, to double check the data

[qlixed]

This will take some extra time and revision of the Python-C api, push to the 2.0 version milestone