Fix typings

[sandersn]

1. Use correct import syntax for 'stream'
2. Rename XMLCharacterData -> CharacterData
3. XMLNode methods return XMLNode instead of XMLElement.

Fixes #211

[coveralls]

Coverage remained the same at 88.469% when pulling 83ff934 on sandersn:fix-typings into f16faa2 on oozcitak:master.

[oozcitak]

I agree on 1 and 2. For 3, a better resolution would be for XMLDocType to not extend XMLNode at all. In that case some methods and properties from XMLNode need to be redeclared in XMLDocType. Could you please modify your PR accordingly:

• Keep 1 and 2
• Rollback 3 so XMLNode methods keep returning XMLElement
• Remove extends XMLNode from XMLDocType
• Declare the the properties type, parent, children and methods document, doc, end in XMLDocType
• Also in attList method attributeType and defaultValueType should not be optional, they are both required. The comment header which says these two arguments has default values is wrong.

Thank you for the PR.

Edit: Also for 2 can you please keep the name XMLCharacterData and make XMLText, XMLComment, etc. extend XMLCharacterData instead of CharacterData. Just to keep names consistent across the library.

[sandersn]

I like the idea of taking XMLDocType out of the inheritance hierarchy. Let me know if that looks right to you.

[oozcitak]

Looks perfect. Thank you. Merging and releasing now.